Hi Mark
Guess I live the closest!!
First stop:
Brighton Marina and all along beach right up to Shoreham (walkable) - parking available on seafront for limited periods - lots of recent sightings of skua, storm petrel, shag, common, little & sandwich Tern, ringed plover, and of course plenty of gull sorts. (good binos needed probably)
Secondly:
Shoreham Harbour and the Estuary - waders, duck, oyster catcher, gull, avocet (if your lucky), tern - check tide times in Evening Argus (local rag) or on-line. Also field & woodland birds: skylark, fieldfare etc Easy to get to by car, straight along A27 or train from Hove or Brighton Station. (15 mins max)
Thirdly:
Chichester Lakes (gravel pits) OS Reserve - parking available - plenty of woodland birds inc. green woodpecker, as well as reed and sedge warblers, bunting etc, cormorant and variety of duck - southside of A27 - possible to walk round for miles. Unusual sightings could include Red Kite, Marsh Harrier - kestrel and Buzzard fairly prolific. Peregrine at Cathedral in centre of City. (about 45 minutes in car - parking in residential area on other side of A27)
Finally:
Pagham Harbour & Selsey Bill: - about 1 hr's drive - parking in visitors car park at Selsey reserve (guide map/leaflet available from visitor's shop in carpark) Wonderful for waders, tern and gull as well as farmland/reed habitat. Plenty of little egret last time I was there, spoonbill (one off I fear which made its way to Pulborough!), avocet, ruddy shelduck, grey plover, blackwit and 06 sightings of osprey, red kite - Ideal for a day out.
That's my local patch in a nutshell!
(oh forgot to say, check 'SOS, Sussex' (use as searchstring) for Recent Sightings