Thanks Ian for those thoughtful tips. I've checked Twickets and they only have Friday and Sunday. Pistonheads might be helpful.
Unfortunately we only get into Gatwick at lunch time Friday so would not make the circuit until about 3pm. The alternative for Saturday is to spend it shopping with our wives in Chichester and I think most here would agree that is not an alternative worth contemplating

hoping to find someone who has tickets but due to changed circumstances can't go and wants a refund.