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As an addendum to the Brighton-and-back idea, I can recommend maybe going/coming back via Eastbourne. I did round trip to Eastbourne last weekend, and discovered (a) where the Ashdown Forest is, and that (b) inland of Eastbourne is a lot flatter than inland of Brighton, because it's on the Eastern extent of the South Downs. (It's still a lumpy ride, mind.) The B2026 from Westerham, through Edenbridge, Hartfield and Maresfield is a very pleasant road and it's easy enough to navigate to Eastbourne avoiding the A22 from there.
If the weather stays nice, go to Brighton and back. It's 'easy' to do in a day per direction, but over two days would be nice and relaxed. Plus, fish n chips and ice cream.