If you go on the Ordnance Survey website. there is a feature on there, similar to multimap etc. However the map info shows at 1:50000 BOATS and RUPPS, in your given search area, and is apparently updated constantly by the O.S.
You cannot print whole page maps but the extracts that are printable are current, and could be useful when planning to drive these routes, for checking against paper maps that may be out of date.
If you are like me and travel far and wide, and like to take in routes all over the country, you don't want to be constantly buying maps.
Thought this might be of use to some.