Hi Mel
We're from Derbyshire too, and stopped at the c&cc site at Polstead. It's about 45 mins to Harwich via Colchester on good roads. We did it on a Sunday morning when the ferry leaves a little later, so you would need to check site gate opening times v. arrival time at Harwich, but Polstead a good site. We've also used a CL even closer to Harwich, about 10 mins. OK for 1 night.Depends what you fancy.