As far as I know, they're open every day mate. They're in a fenced off section of the beach, right on the main seafront, with a café & kid's play area. Cost me £3.50 entry.
Here ya go -just found a link to it:
http://www.bbc.co.uk/news/uk-england-somerset-32167831Runs from now until September.
The town itself's very touristy, (think Blackpool), lots of chip shops, rock shops, bingo halls, amusement arcades etc, but if you embrace the tackiness it's O.K. The beach is great though & they've obviously spent a lot of money making the sea frontage attractive. I was there when the tide was out -might be worth checking that before you go cos I've no idea how far up it comes when it's in. I parked in a carpark actually on the sand at the far end of the beach for a fiver all day.
A very pleasant afternoon out.