Been to this loads as its only an hour from me and it's great, £7 to get in unless you pay for early entry then it's £10. Normally a great selection of cars and bikes on display and you can find some great bargains too.
Went to Newark Autojumble last Sunday in my SIMCA Coupe (Classic/retro vehicle drivers get in for £5). Was the first time I've been for a while, an hour or so from me. Got some good parts including a box of NOS SIMCA parts one of the traders had saved for me. Never tried Huddersfield which is run by the guy who used to run the Newark event before the current promoters.