Include a disclaimer when they register to say that you ONLY provide the service as a meeting place.
Or something along those lines.
You have a utf8 encoding problem, when i entered the £ sign, it came out as £.
The comments have capital letters under by the poster, which doesn't really look right. I can see it's just some CSS that needs work though.
Could possibly add some additional features, such as a buddy list, which, when accepted, shows your buddys AND their email address, with both parties agreeing to the disclosure of information. That would come in very handy if there gets to be quite a few users on the site.
I'm also interested to see how the site handles a LOT of offers, as I do not see any categories, and the search does not cover things such as price.
All in all I still think it's a very good idea, and could become very useful, and I hope that you can use these points to improve on the website.