Don't know anywhere in Sussex, but do shoot at Kent Woodsmen.
Fairly friendly bunch, usually set out a 30 target course on Sundays, that most people shoot through twice, if they so wish. Score cards can be kept, scored on the HFT system, i.e. 2 pts for knockdown, 1 pt for faceplate, 0 for a complete miss. These cards are used to determine handicap for any club comps.
They also field teams in the SE Winter League if your interested in pukka competitions, as well as having a few members who go along to shoot in Grand Prix comps.
Not much else I can say really, other than if you want to give FT a go, you would be given a warm welcome.
HTH