If you want a cheap (well compared to the competition) solution to digital mapping on your PC, try
http://www.mapyx.com/index.asp, they have a 20% sale on almost everything this bank holiday weekend (use code IQYOU).
I bought the full UK 1:50K for £99 some time ago and have been building up the 1:25K tiles as I go along (including the plain).
I've tried most of the competition (Memory Map and Anquet) and I think that this system is easily an equal and for the money you can't beat it. These maps also show BOATS and RUPPS quite clearly.
PS I'll post this in the bargain forum also