https://mikrotik.com/product/sxt_lte_kit
guids for settup https://www.youtube.com/watch?v=qKqCHfS-SeU
https://www.solwise.co.uk/wireless-elevationtool.html
Details on 3g masts;
https://www.mastdata.com/37/37_map_los_address.aspx?Lat=51.9030599&Lng=-0.7166423&AdId=2&Molo=EE
https://www.plus.net/wizard/?p=view_question&id=199972483
Ofcom states that if you have a fault that has persisted for some time, and your provider has failed to resolve it, you can cancel your service and switch to another.
That said, it's not always so easy. Some faults can be hard to prove and providers aren't going to go out of their way to help you do it. Your best bet is to record outages, and phone your provider every time the problem manifests. They'll have a record of the phone calls, which adds credence to your complaint.
If you continue to face problems, you can contact either the Internet Services Adjudication Scheme (CISAS) or the Communications Ombudsman, and one of them will take a look at your case. Read our guide to consumer rights for more on that.
https://www.ofcom.org.uk/phones-telecoms-and-internet/how-to-report-a-complaint/dispute-resolution