Hi Chris,
Yes, as Keef said, go for Lydd.
I've flown from Lydd and Manston, and overhead Biggin, and as said, Lydd will give you most airborne time, and it's also a friendly 'drome. (It will also give you good practice in "airfield spotting" - it's fairly well camoflauged, and doesn't have a sodd!ng long runway to stand out like Manston does!).
I'm in fact starting my PPL this Saturday from Manston!
Good luck whichever field you go to, I'm sure you'll enjoy it!
Llet us know how you get on,
tKF
PS As Keef said, don't be afraid to hang around you local airfields! Ask owners if they want their a/c washing, ask if the hangar wants sweeping, windows want cleaning....anything!
The worst that can happen is they'll say no, but at the best, you might get some flying time in!