I think GowerCharger hit the nail on the head,
YOU LIVE IN NORTH WALES!!!
Why would you even bother? When I lived in Bangor we'd just drive passed beach after beach until we found one suitable to our surfing needs. They're everywhere!
But if you're keen, the scale you'd be doing it on wouldn't harm the environment, (it'd do hee haw for organisms and shouldn't be compared to sunken ships) and wouldn't last long enough to do anything physically to the beach that wouldn't sort itself out.