You don't give us any idea of how old you are or what you look for in a holiday.
But if you like nature and the countryside then I can suggest the North Norfolk Coast.
I went there a few years ago and fell in love with the place.
Very flat of course, but HUGE beaches and HUGE skies and lots of nice old fashioned seaside towns (Hunstanton, Sheringham, Cromer etc.)
Lots of wildlife and great for bird watching.
Pace of life is also slower so it is a great place to have a holiday.