Today was promised to be hot and it was - it's been well over 20C all week and not a drop of rain for over a week.
The part of my garden that was under a foot of water on 7 July is now like a desert. People are watering garden plants!!
However, Tues and Wed are forecast as wall to wall rain but it often doesn't happen (and vice versa of course). If you use the Met Office website the nearest location for which they give detailed predictions is STOWFORD - just by Waitrose.
I'll have a look at the campsite if I have a chance, but I'd wager the surface is baked by now. The general forecast for the week is changeable - maybe more rain to start with than at the end (bad luck for the set-up crews). I would anticipate some mud and stay on the highest ground you can find, unless you like mud of course.
The concern is how far down it is dry - you'll only tell after cars etc start churning up the surface. I'll try and have a look at the Ham too if I have time - that was very slow to drain in recent years - it now sits atop the sewage pumping station of course.