As always it depends whether you are going just for the flying or some other interests.
Assuming the later here is a pleasant round trip.
UK to Lille. You can clear Customs at Lille and either stay the night in town or direct to Lognes. Lille will cost you about 12E.
Lognes is the best airport for Paris in my view. Catch the train into Paris for a few hours or the day as you wish. There is a cheap but clean hotel on the airfield.
Lognes to Rouens - lunch in the City and wander around the Cathedral (some say one of the very best in Europe).
Rouens to Deauville and back to the Blighty.
You could over night in Lognes and over night in Deauville (and miss out Rouen if you wish).
Plenty to see and do, all interesting airports and not to far for an initial foray.