I believe there is a National Builders Federation but it may only be for house builders rather than builders or rennovators of other types of builders.
The National Trust might be worth contacting. They employ lots of special craftsmen on restoring their properties and they might be able to give you a list of the professional firms they employ, or alternatively offer some kind of apprenticeship working for them.
Otherwise try Googling apprenticeships in Building trade, or
something similar. Also, if you have any large firms of surveyors in your area, they may be worth approaching to see if they have any useful contacts in this area.