I have just started using a web site called visitmyharbour.com and I have been very impressed. It gives access to all UK admiralty charts for a flat annual fee of GBP25. They are just JPG images, but you can zoom in and out and pick off waypoints very easily. The site also gives remarkably detailed pilotage notes for just about every harbour around the coast. Provided they don't go belly up like the Wiley online almanac I think it is very good.