muche has been answered but I will add my 2c
NEVER EVER USE CHIPBOARD OR MDF!!!! en of story. PLywood, 9mm MINIMUM, 12mm is better. if your layout will be stationary, you can use sheets of plywood. if you might need to move it, build a 'box frame' with braces, and only place plywood where your tracks will be. the rest is vovered with polystyrene sheets. this allows for a lightweight yet strong structure.
as for track...
you get thin double sided tape. looks like cellotape. you will find it in craft stores - look in the paper craft/scrapbooking section. horribly expensive... use normal wood glue to lay your cork. 1 lesson, split the cork in 2 narrow strips (for n scale about 7mm wide and HO about 10mm wide). draw the centre line of your track. now glue the strips of cork on either side of the centre line, and use normal sewing pins or thumb tacks to keep the cork down. the reason for splitting the cork is to keep it flat when doing curves. the wider the cork is, the more it will buckle when doing a curve, up to a point, and then it will break, or cause crappy track work. in yards and under points, use larger pieces of cork than the track, glue down a sheet in the yard.
also as said, cut the edge of the cork BEFORE glueing down, I use a steel ruler and a stanley carpet knife at an angle.
