this one was so much easier to understand than the one above!
only to get to where the person above was saying you need to go settings > mobile network > edit/add apn (appearing at the bottom of the screen) > and then type the things stated above
Thanks to falirkfc! Finally found what I was looking for - found mine under 'mobile network' in settings, then 'edit apn' at the bottom. didn't even have to reboot for it to take.
My first experience of the community; good one, take a bow.