That just happened to me, It fixes itself in a bit.
The chatroom is a little finiky at times, I have found if I do the following it makes it a bit more reliable to get in to:
Click the Chatroom link from the Homepage - http://www.naturalbushcraft.co.uk/ and don't click anything else until it's fully loaded you in (might take 10-15secs). Should work, if not click in your address bar (where the URL is) and press enter to reload the page (again don't click anything whilst the chatroom is loading or it can stop it).
Hope that helps,