It might be necessary to ensure that your exit node is not in the UK or another locality that is otherwise blocked.

That procedure depends upon your platform and client.

http://www.b3rn3d.com/blog/2014/03/05/tor-country-codes/

Edit: Use this link instead (thanks mzajc!):

https://web.archive.org/web/20180429212133/http://www.b3rn3d...