twin power socket by phone socket

I think I need to have a twin power socket next to my incoming phone socket .I have an extension phone socket which could have a twin socket next to it, would this be alright.

It depends what quality cable connects the extension socket to the master socket. With normal telephone extension cable the answer is no.

But the modem and your router do not need to be close together. They are connected using standard ethernet cable, with a maximum distance of 100 metres.

The basic setup is with the FTTC modem connected to the master, which has an interstitial faceplate fitted to filter the phone and VDSL2 signals, using just the short VDSL cable supplied. See this pic.

There is a "Home Wiring Solution" (also called a Data Extension Cable) that you can order at the time you order FTTC. Some ISPs order it for you automatically just in case it is needed, others don't.

With that cable, (instead of normal stuff), the engineer can site the modem up to 30 metres (internally or externally) from the master socket and install a socket for the modem to connect to. But that means him fitting that cable at installation time and you might not like the look of the result.

Alternatively, using the same new cable, he can move the master socket to a more convenient place.

a 2 or 3 way adapter will suffice, the power demand is small but two boxes need two sockets

Demonstrated by:-

Our third bedroom has one power socket, near the door. Into this is plugged a two-way adapter. One socket of that is used for the vacuum cleaner for the landing and sometimes the other two bedrooms. The other has a trailing lead plugged into it going round the walls to the diagonally opposite corner, ending in a 4-socket strip. Two more 4-socket strips are daisy-chained off that.

Connected and permanently powered up are the DECT phone base station, the modem, and the router. Also permanently connected are an All-in-One HP inkjet printer (usually on), a 500GB network disc with the printer connected to it - also usually on, and a shredder.

Occasionally connected are the second laptop, and also occasionally this laptop which is normally downstairs. When this laptop is used up there all except the shredder are likely to be powered up and in use.

The setup has been like this for years with no problems.