What would be the perfect day out for you in the coast in the South East of England? Realistically i could drive anywhere on the coastline between Portsmouth to Dover.
I would go to Rye a lovely place, or on to dungeness and go on the romney hythe and dymchurch railway, lovely ride through the romney marshes, or if you want a quiet beach, the one between st marys bay and new romney is superb, so many places to see, or you could go to camber sands, hope you have a great day out, Ray
Brighton is a very elegant town. Portsmouth is good; you get a view from the new tower, and you can wander round the dockyard looking at HMS Victory etc.