Bloop if you are really unhappy with your GP and strongly want to move, I'd suggest writing a complaint to your local Clinical Commissioning Group. You should have other options, see this link:
www.nhs.uk/NHSEngland/AboutNHSservices/doctors/Pages/patient-choice-GP-practices.aspx
The other practices don't have to take out of area patients but they can. And the nhs commissioners would, I believe, expect you to have a choice and would not be very happy if all the other local GPs refuse!
I'd write and say that you understand that you should have a choice of GP practice but you are finding that you can only register with the one GP practice where you are 'in area' and that all other local practices that you are interested in have declined you (you should probably cite their names, and ideally have tried to register with 2 or 3 alternatives, if geographically feasible. Therefore for where you live, you do not in practice have any choice and can only register with the one practice. That you have been registered with them for x years, not happy are unable to move. While accepting out of area patients is discretionary, do the commissioners have a view on your predicament, and any ability to request or require practices to accept out-of-area patients where they otherwise have no choice?
Address the letter to the lead commissioner for primary care (address for the CCG will be available up on google for your area).
I would be very surprised if they dibg expect gps to be reasonably flexible and would put pressure on. Worth a letter anyway, if you are really fed up. You've got years of taking baby to the GP for all manner of childhood ailments, it's a massive pain if you don't like your practice!