100 Nautical miles is a long way per day, though your half way point will be near Eastbourne which is a lovely marina (sovereign Harbour).
Be wary of Selsey Bill, I suggest going wide.
Obviously lots of shipping in the Solent and Thames Estuary, so be super wary of that (cue a chance for me to flog you an AIS receiver).
It should be a good trip, lots of interesting stuff to see on the way too.