4g home internet

Hello everyone, I am seeking some advice regarding 4g routers and antennas. Basically, i'm looking for a router and antenna to stick in my loft as BT landline speed has dropped from a whole 3mbps to barely even 0.5mbps and they want to charge me hundreds to repair it, I'm not keen. Its not my fault lightning hit something! haha.
Thus far I've set up a TP-link router (MR6400) on a three mobile contract (allready saving £25/month with that, not looking good BT!) and its giving me 10mbps which im happy with, but I believe I can get better speed with a different router and external aerial attached?
I am looking at a Huawei B315 on Amazon at the moment, notably because it has a connection for an external aerial. Question is, which aerial is good?
I'm about 7 miles from the mobile mast and can see it on a clear day. No matter what mobile/router/pocket router I have the three simcard in, Its a struggle to get better than 2 bars of signal.
Essentially I'm just interested in what router/aerial combination people are using. Perhaps the B315 is junk? I don't really know because all of this is new to me! Hope to hear from someone soon. Cheers

I haven't tried it yet, but I'm seriously considering the MicroTik SXT LTE. May be worth reading up on that - check the 4G frequencies that are available to you. A good 4G external antenna costs half as much, so it seems reasonably priced to me. Maybe others can comment?
A bonus for me is that it can natively make a L2TP vpn connection, which I currently use with AAISP's L2TP service to give a static IP address over 4G.

I am currently using the B311 Wireless Router which comes with the Three HomeFi package.
It is a Huawei product very like the B315 but has only one Ethernet port at the back.
I have connected to this a Poynting 4G-XPOL-A0001 Antenna

My speeds, with Three, are 100Mbps down and 30 Mbps up but the mast is only a mile from my house.

My ADSL speeds were 1.5Mbps down and 0.5Mbps up so I just got the telephone line disconnected as no hope of fibre.

In reply to a post by sheephouse:

I haven't tried it yet, but I'm seriously considering the MicroTik SXT LTE. May be worth reading up on that - check the 4G frequencies that are available to you.

LTE Bands 3 and 7 would limit you a bit. Primarily Three and EE use Band 3 for the bulk of their 4G deployment. Band 7 is expansion for both EE and Vodafone. Band 20 (800 mhz) is needed for rural areas, and for the main deployment on O2 and Vodafone.

Probably better to get a different LTE modem that plugs into a router via ethernet?