Well... you need a) security, b) weaponry, c) food.
Weaponry is the most important, because if you're stuck somewhere you're eventually doomed to starvation or lacking other necessities, so you'll to protect yourself to move around. Therefore first stop is anywhere that you can get - preferentially - guns. Even in mostly weapon-free Britain, there are plenty of accessible gun shops, gun clubs, police and military buildings. In the middle term, the best place would be the nearest military camp as it should have fortified buildings, food stocks and (obviously) guns and ammo, which buys you time.
Also, hopefully, it will have armoured vehicles and radios, which will be pretty important: eventually food and ammo will run out, and you'd want to look at gathering other survivors. Then you want to get yourself and the other survivors to an island (not one with a bridge) small enough to not have a huge zombie population but large enough to support the survivors. Clear out the zombies on that island, and - in theory - that island should be almost permanently safe. Then farm until the zombies decay - presuming they decay do and die eventually. If they don't, the long term community objective will be to repopulate and clear out other islands and settle them, and eventually the mainlands.
Weaponry is the most important, because if you're stuck somewhere you're eventually doomed to starvation or lacking other necessities, so you'll to protect yourself to move around. Therefore first stop is anywhere that you can get - preferentially - guns. Even in mostly weapon-free Britain, there are plenty of accessible gun shops, gun clubs, police and military buildings. In the middle term, the best place would be the nearest military camp as it should have fortified buildings, food stocks and (obviously) guns and ammo, which buys you time.
Also, hopefully, it will have armoured vehicles and radios, which will be pretty important: eventually food and ammo will run out, and you'd want to look at gathering other survivors. Then you want to get yourself and the other survivors to an island (not one with a bridge) small enough to not have a huge zombie population but large enough to support the survivors. Clear out the zombies on that island, and - in theory - that island should be almost permanently safe. Then farm until the zombies decay - presuming they decay do and die eventually. If they don't, the long term community objective will be to repopulate and clear out other islands and settle them, and eventually the mainlands.