Apart from the space blanket element I think OS already do this. I recently subscribed to the OS Getamap. It allows you to plan, create a route, export to GPS and print a map and a routecard. The new system currently in Beta allows you to print up to A3 size. What I've done is print 1:25 000, then 1:50 000 of a larger area centred on the same location. I then laminate them back to back. I use the printer at work which is laser so great quality, I make a donation for each one I print. I work all over the country so this allows me to print maps of different walks I do. It's £19.99 for a year, I thought I'd give it a go. The software is great displaying great quality aerial views, unfortunately map info can't be put over the aerial view.
