You can tell Kitch doesn't drive anywhere!
If you are coming down the A3(M) stay with it (as the man said) until you get to the A27/M27 and head West - past Portsmouth in the general direction of Southampton.
Take jct 10 (Fareham West?) - the slip road takes you onto the A32 (heading in the right direction!). There are several roundabouts - the one you are looking for has a petrol station ahead of you as you approach - take the first exit and go straight through the village of Wickham. You will go through a couple of sets of traffic lights, pass BTA Car Sales on your right and then the road sweeps round to the right past a big farm shop. Take the next left (A334), signposted to Botley. Pass Wickham Vineyard on the right, about half a mile further on you should spot the signs for Ambush - the site is on Raglington Farm on the left hand side of the road. If you pass Silver Lake garage on the right, you have just passed it!
Postcode for site is SO32 2HL if you have SatNav that works that way.
Have a good weekend one and all!