.. .. .. I know and you don’t want to spend a fortune on taxis getting to the “attraction” nor should it be too far from the airport .. .. ..
Here are a few personal favourites.
Bembridge - the Crab and Lobster is superb for a sea food lunch, and it is 20 minutes walk away along the beach, or £5 in a taxi. The beaches are beautiful too.
Cambridge - a beautiful City to look around, good shops and punting on the Cam to boot. There is a bus from outside the GA terminal into the City centre - about £1 I think.
Peranporth - a trip too the Eden exhibition - a bit further I know but a hire car for the day is not too expensive.
One for the kids - there are a couple of possible airports for Alton Towers within 30 minute taxi ride or again hire a car for the day at East Midlands.
L2K - of course a favourite, hire bikes at the airport and ride into town for lunch or a stroll along the beautiful sandy beach. The supermarket is 10 minutes from the airport for cheap beer, good cheese and wine.
Elstree - mainline or tube straight into London, the best airport for the capital in my opinion.