Current provisional information for 2013 NHC shows can be found on the website of Towy Vale hamstery as it arises and will appear on the NHC official website when confirmed. This website also contains details of past shows, results etc. Hamster Forums are also a good source of up-to-date show information.
The map below shows the distribution of NHC affiliated hamster shows in the UK at the present time - as you can see, Leeds is currently the best place in the country to be a hamster devotee! Apart from one show in Cardiff all shows are held in England, with a bias to the south within the Northern club's range and to the west for the Midland and Southern hamster clubs (though not as far as Cornwall!).