Blackpool
If you have the time you could even visit Blackpool while you are in the area, just further up the coast. Maybe about an hour at the most in a car. Its approximately 35 miles, but because of the estuary you have to go by road on the A59 to Preston and then the A583 into Blackpool.
Here is a pic taken where you can see Blackpool Tower in the distance.

Entrance
The Cyclone Rollercoaster
St Cuthberts
The Pier