[cable]

Areas currently with 5G tend to be the same as where 100MB or much faster is available.

Typically where it can reach fibre backhaul yes. I could have 900up/900down with a certain Hampshire based provider for £25.

However the the eventual plan is to replace copper with fibre, currently being rolled out by Openreach, through Project Mustang replacing the Virgin Media HFC network (around 2028) and maybe builds by altnets like Cityfibre which will eventually merge like the original cable netorks did. So by the early 2030s its should be much more accessible.