has anyone used the IRS walkin help desk at the US embassy in London?

I am having sooo many problems with my current [expensive!] accountant that I am wanting to sort my US taxes out on my own. I am, however, basically clueless. I know that the US embassy in London has a helpdesk for IRS issues and was wondering if anyone had used it before and found it helpful? If so, can you give me the scoop?

Cheers

just an update - i used the helpdesk and have to say i was very impressed. the people there were very relaxed and happy to help. i felt like i got real 'american citizen service' - after living in uk for almost 8 years i'd almost forgotten what that was like