Yes UK is in Europe and I think will be for the next few million years - oh you meant the Political body - the European Union. Oh yes we're still in that and will be for a few years at least.

As to the landline number, you can keep your landline number if you don't move into an area where the phone numbers 'region' code is not applicable.

Just like I am sure that is the case for every other country in the world (or thereabouts).

I am curious to know with regard to USA phone numbers where I cannot tell a mobile from a landline by just looking at the number (e.g, UK Mobile numbers can be identified because they are 07xxx numbers) but US mobile numbers look like landlines and have the same area code.

Can you move to a different state and keep your number even if the area code for that state is completely different?