I've heard East Yorks is nice
There's loads of places to see.
York
Oxford
Stratford Upon Avon
Cotswolds as mentioned
Cornwall
Devon
Dorset
Kent
Sussex
The list goes on....
As Ricey said Brugge is a wonderful place and literally 1 hr from the eurotrainthingymagigy.
Why not pick up the boat from Hull, head to Hoek of Holland, stop off at Ansterdam for a cup of herbal tea, head onto Brugge for a night and come back via the trainthingymagigy, stopping off at Kent, maybe lakeside for some shopping, head up to Oxford or Cotswolds.
Decisions decisions.....