Get it sorted asap Lilybet, from memory they need a weeks notice so you may need to pop back to check for mail early next week. And they were a right bugger with me as we'd just got married and they refused to redirect anything with my maiden name on, as I didn't have current ID.
Like Mrs B said they are thorough with what they will forward but it is a life saver when you move house. I had to pay double as me and OH are not married and have different surnames so that was quite annoying!
To be fair we don't actually complete on the house until Monday 9th even though we are moving this weekend (the landlord wanted us in ASAP) so I can pop back to collect post until we get it set up. Seems like a bargain actually because I'm never gonna remember to notify everyone!