The Unifi UAP-AC-M is a really good piece of equipment for this scenario, certainly. If it's externally mounted it will probably provide excellent coverage inside the summer house and in the garden too. I've recently used one just like that.

Caveat emptor:

While configuring Unifi equipment isn't rocket science, it requires a better technical understanding than the average consumer access point - because it isn't a consumer product. It's not really something many traditional electricians are going to be able to configure easily - or at all. What you don't want to do is have someone who charges you by the hour, and takes a long time because they're clueless and take ages to get it working, and even then not properly.

Advice to the OP - the Unifi UAP-AC-M is a really excellent choice for this use but either get someone who has Unifi experience to set it up or take the time to learn how to do it yourself. You can practise configuring it all inside the house before it's set up for the summer house.

If it's mounted on the outside of the summer house, it will need a short length of electrically shielded external grade ethernet cable to connect it to the inside of the summer house. Regular PVC jacketed ethernet cable will quickly degrade in sunshine. You can buy external ethernet cable by the metre from Broadbandbuyer or MS Distribution under the name Tough Cable Pro. It also must have shielded RJ45 connectors and the shield must be earthed - either through the supplied power supply or better still via a separate ethernet surge protector like the Ubiquiti ETH-SP-G2. If the Cat5e cable that runs to the house doesn't have a screen with an earth wire, you will either need to put the mains power supply in the summer house or put an ethernet surge protector there.

Final point about outside mounting: You must configure the access point for specific outdoor use in the Unifi controller.

Good luck with what ever you decide to do and come back with an update or further questions.

In reply to a post by jabuzzard:

I feel an experiment coming on with an extension lead and long patch lead. Unfortunately I have a feeling I don't have any long patch leads at home and of course I am WFH at the moment.

In my experience, patch cables become unwieldy at the 20m length point. I now make up 15m ones and use Cat6A shielded couplers

Hi the CAT5 is down through a separate conduit from the electricity. If I ask the electrician to change the face plate on the socket in the summer house to a network face plate, and install a new back bod and network face place in the house and wire the CAT5 cable into there, will this work? I will connect the main BT router from the network face plate in the house to an LAN port on the router and then in the summer house cornet the router to the WAN port and set it up as an access point - will this work?

If you already have WiFi from another source, (which the OP does) you can just install the UniFi app on a phone or tablet and set it up from there as a stand alone device. There is no requirement to touch the UniFi Network Controller software. It is frankly no harder than any other sort of access point and certainly easier than turning a router into an access point. You can then use the UniFi app to keep the firmware updated.

In fact if you have a working DHCP server on the network you can even use a USB on the go adaptor and a USB ethernet adaptor to get it setup with a suitable Android device. It's how I set mine up, though I did have WiFi access at the time, I turned it off to see if this method would work in case I had to reinstall from scratch down the line at which point I would only have UniFi access points

While it is outdoor rated the UniFi AC-M is not IP67 and needs to be in a sheltered spot. Personally I would put it inside the summer house which is likely to be timber only and offer little attenuation of the signal.

If you power it using PoE from the house there is no requirement for shielded Cat 5e/6 cable. There is plenty of unshielded external grade Cat 5e/6 available on the market. I am not saying it's a bad thing, just not absolutely necessary as there is no reason to expect a static buildup. The Ubiquiti tough cable is more targeted at the fixed wireless access market with devices attached to top of tall masts where static buildup is a concern. There is of course no harm in using it other than to your wallet.

I would however at this juncture note that even if run in conduit and it does not go outside the summer house you need to use an exterior grade cable, and even then not all exterior cable is suitable for running in buried ducts. Ordinary Cat 5e/6 is certainly not suitable at all for running in buried conduits. At a minimum you want something that is gel filled as ducts often fill with water and standard Cat 5e/6 and not all exterior grade are rated for immersion in water for extended periods.

Personally I would always go with SWA to give myself some spade protection for anything under ground. Once it comes inside remove the SWA jacket for ease of use and seal the end of the SWA to the internal cable with some adhesive lined shrink wrap tubing. Usually the internal cable has an outdoor rated jacket but worth double checking.

In reply to a post by Sam1234:

Hi the CAT5 is down through a separate conduit from the electricity. If I ask the electrician to change the face plate on the socket in the summer house to a network face plate, and install a new back bod and network face place in the house and wire the CAT5 cable into there, will this work? I will connect the main BT router from the network face plate in the house to an LAN port on the router and then in the summer house cornet the router to the WAN port and set it up as an access point - will this work?

If that is the requirement that meets your needs and you are happy with a simple set up then yes, that will work.

thanks funkydan I am looking for a simple set up. Final question, if I set up the second router as an access point in the summer house, can I wire a laptop to the router as well as using it wireless ?

Routers running as access points usually allow this.

You're welcome. I'm not sure. I have never set up a router as a wireless access point and don't know what settings you would need to change on the summer house router. I wouldn't like to guess.

Some routers e.g. Asus actually have it as a menu option, don't recall what router model you were planning to reuse.

I would recommend if you've not done it before to do the initial configuration of the router into access point when within a few feet of existing router, to avoid lots of back and forth. It is fairly straight forward but like lots of techy stuff first time is always more stressful.

http://www.coolwebhome.co.uk/wap/configuring-wap.html is a few bits on repurposing a router that does not have a built in access point mode.

In reply to a post by funkydan:

You're welcome. I'm not sure. I have never set up a router as a wireless access point and don't know what settings you would need to change on the summer house router. I wouldn't like to guess.

Only crucial one is to turn off DHCP, and if the WAN port is an ethernet port, NOT to use it. Otherwise things can get complicated.