Toughness: 6 out of 10
Trains: 9.54 train from Victoria (10.01 Clapham Junction, 10.10 East Croydon) to Lewes, changing there (be quick! - arrive 10.56, depart 11.00) for the Seaford train to Southease, arriving 11.07. For a more relaxed journey, get the 0924 and have a coffee at Lewes.
Trains back from Seaford are at xx25 and xx53, connecting for London at Lewes.
Buy a day return to Seaford (Sussex)
For the morning: Directions, GPX, map
The idea of this walk is to do the shorter version of Book 2 Walk 26 Southease to Seaford - ie, omitting the river loop to Rodmell - as a 7.6 mile morning walk across the downs to the sea, arriving at Seaford for a swim(??) and lunch. Low tide at Seaford is 11.37, but apparently this shingle beach is swimmable at all tides.
Those that wish could, of course, terminate the walk here. Otherwise an afternoon walk over Seaford Head and up the Cuckmere River to Exceat (3.9 miles). Directions/GPX are not really necessary for this: follow the seafront and then the cliff top path to Cuckmere Haven and then turn left up the Cuckmere River to the road bridge.
Tea at Exceat is possible either at the Cuckmere Inn or - by turning right over Exceat Bridge and walking 400 metres up the road - at the Saltmarsh Cafe, open to 5pm, in the Seven Sisters Country Park Visitor Centre complex.