I agree with Magnum, the Seachest outfit here in Plymouth have an excellent range of charts available and a well deserved mail order reputation. I've never stumped them yet.
Beware though if you call in personally, they also have a huge selection of sailing books of all sorts, so expect to spend a few hours in there if you're weak like me!!
I thought you were based in this area somewhere, if so, popping in would be the best bet.
I've placed my order with Seachest. They weren't the cheapest, but there wasn't much in it. Above all they had the latest edition in stock, and they undertook to despatch it today.