We put a picnic blanket down so it wasn't so rough on his knees. He mostly wanted to eat pebbles though tbh...
A lot of the pebble beaches have hidden sharp things in the pebbles, I’d be really careful, I’ve seen too many accidents happen with young children. However, you can maybe work around it and put something really thick down. Just a crawling baby that isn’t crawling on a flat surface might be a bit of a nightmare
Me and my siblings were basically raised at the beach Only issue our parents have were us wanting to put everything in our mouths