One of the things I love about living in London is that sea salt is just sea salt and is cheap enough that it isn't a special item, to be used sparingly. It's just salt.
When my mom visited me in Toronto a few years ago we found Malden Sea Salt at the St Lawrence Market. It was stupidly expensive but mom bought us both a box and I used it (thriftily) and thought it very special. Fast forward to Tesco and it's cheap! Love it.
Incidentally the website is actually really interesting. Check it out.