nearest hotels would be in the city centre. not sure about the parking though but some do have definately have it and i don't know if they cahrge extra or not
City centre is your best location, last year there was ques of taxi's outside after a concert we attended. So you'll have no problem getting back to hotel.
jurys inn would be the nearest with parking i should think. it will take you about 15 minutes max to walk to the showgrounds. if your half bladdered - 40 minutes