Deanland is the nearest. Ppr, 500 metres, 15 minutes by taxi or a 5 ish hour round trip walk along the south downs way. No problem with overnight parking. There is a strip just south of lewes but it is further and more difficult. Interestingly there use to be an airfield at friston and the strip is still in very good condition but long since closed. It would be fun to get the farmers permission.
Anyway in terms of nearest deanland it is, after that it is a train journey to eastbourne from somewhere like shoreham, or redhill, or maybe even headcorn all some distance away and pretty pointless flying really unless you are coming a very long way.