In reply to G1STQ:
I also recommend Streetmap; copy and paste the grid ref and remember to remove the space that is inserted for some reason on the SOTA pages. I print the 1:50k and it comes out oversized so that I can easily read it. Sometimes I print the 1:25k (also oversized) because it shows fences and Access Land which is very useful both in seriously wild areas (walls & fences) or farmland (for access).
Dave, M0TUB is absolutely right when he says get the postcode and then check where it actually points to; on several occasions I have had them relocate to the other side of the hill! What I then do is choose another farm further down the hill on the side I want to be on. I write this and various other info on the page margins of my printouts (in pencil) so I have the locator and WAB square to hand when working.
Map cases normally either leak or disintegrate or both. I have an Ortleib which just fits an A4 sheet and so is ideal for my printouts (as well as maps refolded). Horribly pricey but well worth it if you don’t lose them; managed to keep this one for two years still watertight. (Usual disclaimer - no connection with the firm etc.)
If you do buy maps either trim the cover just smaller than the fold or remove it altogether before refolding or the cover will burst the map along the fold lines. Harveys recommended if there is one covering the area. Printed on polyethylene, I think.
Expensive GPS with 1:50k installed does cover the area you visit even if you left the map at home. Snag is cost (think good 2nd hand 817ND) and small screen. Plus point is that you can magnify so large that the trigpoint fills the screen.
Hope there is something useful there; been hill walking for 50+ years so hope I have learned something useful.
73 & safe walking,