Curtis Marine in Plymouth specialise in classics - believe they advertise in Classic Boat. Mind you, if you expect to be refitting for any length of time, you might ask the people at Gweek Quay who is popular there. Remember, the vast majority of brokers are really acting as agents of the insurer and if it doesn't fit their pricing model, you just end up with a stupid price, rather than "sorry, not for us" so it can be a bit misleading.