Skegness. It's about 15 minutes walk to the beach. The airfield is actually at Ingoldmells where Butlitz is. There's the beach, stacks of amusements and guff if it rains (Monday is looking good) and eateries by the million. I take my 8 year old grandson there and he loves it.
Clacton is much the same, although might be a bit of a drag from Blackpool, plus it's a fairly short grass strip, don't know how much your starship needs.