The county shows are normally fantastic for stuff like that, when i was at Kent show with my dog i saw 'Paws in the Park' advertised which is on at the same showground
20 - 21 September 2014 Kent Showground, Detling, Kent
16 - 17 May 2015 South of England Showground, Ardingly
here is the website, it looks great http://www.pawsinthepark.net/
Paws in the Park is a huge show with loads of dog related stuff. There's Discover Dogs which I think is October/November in London. You've missed quite a few as they usually take place in the summer but Paws in the Park is definitely worth a visit.