My brother (TGSC) and I used to have a 4ft square sheet of chipboard that was vaguely green (not grass green, just slightly dyed green). It was fairly cheap from the local timber yard. We also later added four
2'x4' modular terrain boards at a later date. Neither of the surfaces was quite as good as that, but they worked and you didn't have to worry too much when you put it away.
As for scenery, I think most of ours was home made. The
Industrial Complex is one example, although we also had some bunkers made from templates in White Dwarf, a few ruined buildings made from the old polystyrene boxes, hills made from polystyrene, plus walls from the 2nd Edition box and various cutouts from White Dwarf.