How can you receive mail while cruising?

One of the things we looked into a while ago was what to do about receiving your mail if you don't have someone who will allow you to use their address for your mail. There will be things that will need to be sent like bank statements, insurance documents, BW licence etc.

We've discovered a service called UKPostBox.com.  They give you an address to use for having your mail sent and then forward the mail on to wherever you want.  Or... they'll scan the mail for you to read.

There are various payment options : Pricing
For most people in our situation there wouldn't be a large volume of mail so the pay as you go service would be the best for us.

So the next question is how to get the mail from UKPostBox.com.  Royal Mail offer a service called Poste Restante where you can have mail sent to a post office and then collect it from there.  Royal Mail say this service is "subject to operational capability".  I guess that means you'd want to ring ahead to the post office and check that they will accept your mail on this basis.
More info :  Poste Restante