We would be going if not for the fact we have been camping the last 2 weekends and got a soaking for packing up the first weekend and the tent nearly blew away and I stood on a tent peg (ouch!) while pitching in strong winds second weekend
The weather looks ok, a bit showery! You may be lucky and stay dry. I can recommend a trip to Tonbridge Castle, quite cheap and audio commentary thing included. Ds's loved it.