Chris
If you check the join a club link on this page you will find the names of clubs across the UK – there may be one near to you in sussex. Len is referring to Princes Park at the Eastern end of the Eastbourne seafront. This is salt water, but I believe there are no restrictions on running model boats.
Hove Lagoon (at the Western end of Brighton seafront) is also a public boating lake I believe and nearer to you. The only difficulty is that both these facilities are quite large and consequentially can be quite rough if the wind is in the wrong direction.
Otherwise, why don’t you telephone your local Parks Dept., and ask what is available locally?
Paul Freshney
Editor