I am not completely sure but I think the site you are posting you have to pay to join. Though some people may not mind that.
I think it is nearly £20 for subscription, which isnt a lot but some people may not be able to afford it.
That is a very good site - & £20 will usually pay dividends in the information helping you get what you are entitled too. I wish I had used this site when I put in my DLA Claim.