If you have a consumer unit with circuit breakers, do you still have to use a shaving socket for shaving, or can you just use a European adaptor and a standard outlet?
If it's in the bathroom you will have to use a shaver socket. It is a isolating transformer that has the same number of turns on both primary and secondary winding therefore the supply to the shaver is not directly connected to mains but induced through the transformer.
The regulations changed recently in that you can now have a normal socket in a bath or shower room provide that is is at least 4.2m from any water outlet. As this is a bit impractical for shaving, you still need an isolating transformer.
I've travelled quite widely in Europe and elsewhere, and the UK seems to be the only place where you won't find a normal socket in bathrooms.
Tweed is spot on, bathrooms are dangerous places so thats why an isolating transfomer has to be used. As for anywhere else in the house, a simple adaptor is fine