You have three directions, North, East and West. South will require you to take up swimming.
That
@User13710 knows of what she speaks, in all matters.
@rich p can also provide wisdom in these matters.
For me, very much an ex-Brightonian, the answer is always up and over the Beacon then peel off through the lanes of the Weald in direction of say, a Henfield, or an Uckfield, before turning south, hitting the coast via one of the river valleys that pierce the Downs, and then steam along the seafront to home. Stay off the A roads, as far as possible, the drivers are awful, and use the A23, A27 and A24 only where there is a cycle path (and with earplugs in to dull the road noise of the incessant traffic)
If you don't ride the entire length of Underhill Lane at some point you are bonkers in my book.