Sorry, just spotted this post! The Beau, in European service, didn't wear the 'black' scheme for very long, changing to the general night fighter scheme of overall Medium Sea Grey, with a disruprive pattern of Dark Green on the upper surfaces, like the Mosquito, although there were, of course, some variations. The 'Warpaint' publication "Bristol Beaufighter" has some good info and colour schemes, and of course the 'SAM' book on the Beau, and how to model it, is another good source. As for decals, apart from the national markings, in general you'd only need Dull Red code letters, and either Night ( black), or Dull Red serial number/letters, both availbale from various manufacturers as decal sheets.
Hope this helps.