Changing from one PAYG provider to another but keeping number

Frozen_up_north

See https://www.ofcom.org.uk/phones-and-broadband/switching-provider/switching-mobile-phone-provider

An older model phone is unlikely to have all the latest frequency bands used for 4G and 5G networks. Some providers used to offer coverage maps based on the model of phone, but I don't see any with that feature now as maybe there are just too many models to choose from.

Anyway, what model of phone are you using?

GiffGaff use the O2 network and are pretty good.

Neil49

I would start by asking your neighbours who they use and what issues they get (if any). Where I live we have a local Facebook group and this question comes up occasionally. 

You could have a mobile phone mast close by but if it's with EE or Three then that's of no use to you but could be ideal for your visitors.

Try doing a search on mobile phone masts in your area.