
To add to what has already been said: You can find show schedules on certain websites (some can be entered online, but not all), you find show schedules AT shows, some ringcrafts have schedules available, shows are advertised in the two weekly newspapers Our Dogs and Dog World (available by subscription, some large newsagents stock them or you can ask your local one to order them for you, published every Friday), and you can buy the Starprint Diary which lists all shows for the entire year complete with location and contact details. I will try to give all links!
For showing your pup needs to learn to walk nicely on the lead, stand still, and to be stood (in your case on a table) to be examined by the judge, touched all over, teeth checked etc. This is what you learn at ringcraft.
http://www.fossedata.co.uk/ Fosse Data, has schedules and online entries (and results) for championship shows and some open shows.
http://www.highampress.co.uk/ Higham Press, schedules, online entries and results for some championship shows.
http://www.cidweb.co.uk/ Canine Information Directory, a smaller number of shows with schedules and online entry etc.
http://www.arenaprint.co.uk/shows.html Arena Print, lots of schedules for Open shows.
http://www.ourdogs.co.uk/ Our Dogs newspaper
http://www.dogworld.co.uk/Dog World newspaper
http://www.thekennelclub.org.uk/item/265 Article from the KC about starting in showing, includes a link to find local ringcraft classes (note this does NOT list all)
The Starprint website appears to have been hacked! But if you search for Starprint dog show diary on Ebay you will find it there.