The mice being shown usually have to be processed and on the bench by 10am and the judging starts about 10.30. It seems to depend how many entries there are but everyone has a break for lunch before judging the best in show.
Theres sometimes not much to see as the mice tuck themselves away in thier maxeys, the best part is watchign the best in show judging and the bit just after when most of the breeders are happy to show you their mice.
I think it's more than that this year Sarah - there's a link to the show website on the Upcoming Shows section here, that should tell you everything you need to know. It also has schedules for all the different animals being shown there, so you can see what there will be apart from mice.