Mine had already been pretty well prepared for Ford Fair anyway (T-cut, Poorboy's All in one Polish with Sealant and Collinite No. 476), so only needed a wash when we got there. Dal used Meg's Clay kit, ClearKote Vanilla Moose Glaze and Poorboys Ex-P a week or two before.
It depends how confident you are in your own cleaning abilities if you do it yourself. The lighting does hide a multitude of stone chips.
Ed's installed a hose pipe fairly recently, and can provide a bucket of warm water too. He'll also supply free tea and coffee 'cos he's nice like that!