Whether or not your front door needs to have any fire resistance will depend on a few factors:
1. If the common parts are enclosed, you will almost certainly need some fire rating, both to protect your flat from fire outside and to protect others’ escape route from a fire in your flat.
2. If the common parts are external, then you probably don’t need any fire rating to the front door unless the deck/balcony/whatever outside are someone’s only means of escape. If this is the case, then any windows facing onto the common parts would also need to be fire rated.
If you call Camden building control you might be able to get some advice – these days they are often too busy to take calls unless one has paid an application fee, but you may get lucky.