which door frame?

as above i need to replace a door frame in my house to fit a 30" door looking at wickes they do 2 sizes 27 x 106 or 27 x 131 which one wouls suit what i need?
also while we are on doors i have one door in my house 70" tall can i cut down a standard wood door to fit? or does anyone know where i can get one made to fit?
cheers all

there are door frames, door casings and door linings.

lining and casing widths vary to suit varying thicknesses of walls.

there are 27", 30" and 33" wide doors available in imperial sizes. these are all predominantly 78" tall.

most internal imperial doors will only tolerate the removal of 12mm from each end (top and bottom). to achieve a 70" tall door means you will have to cut the bottom of the door and re-site the bottom rail using glue and clamps