multiple domains, is there a point??

is there a point in buying multiple domains ie, mysite.co.uk mysite.com, my-site.co.uk etc and have them forward to the main site??

The main point would be to cover misspellings etc. and people who don't quite know the right domain, and to keep others from taking a name that could be confused with yours and doing something that would hurt you (like a scam or a competitor).

is that all?? no search engine benefits??

That is probably also a factor. An SEO expert could say more about that aspect.

No SEO benefits. Worse do it wrong and it could harm your search engine rankings. Google likes unique content. You can get penalised for content that duplicates that on other sites, even if those other sites are your own.

Benefits are for mis-spellings and to shut out copycats if your sites are successful, but make sure that you're clear which is the master domain and point the rest to that domain with 301 permanent redirects.