John:
I will assume you know about the London Cigarette Card Co. but if not:
http://www.londoncigcard.co.uk/
then there is Murray Cards:
http://www.murraycards.com/books/reference.aspx
and also the Cartophilic Society of Great Britain:
http://www.csgb.co.uk/
All well worth looking at. There is also a great A&BC/British Gum Card gum site here:
http://cards.littleoak.com.au/index.html
The Vintage Non-Sport Board (link above in the upper left corner) has some UK collectors I am sure and they can offer more information if needed.