Very useful information, thanks for that.
I'd like to add
uknumber.co.uk - Giving you a free UK phone number - wherever you are in the world! which gives you a free 056 number in the UK. The advantage over 084x, 087x, 070 is that 056 numbers are supposed to be charged at standard landline rates for the calling party in the U.K. (I say "supposed to" as this is the way it should work in theory, but it depends on the provider).