i recently did mine. (On a GC8)
there is also a diagram somewhere on the net (That I cant find now) which shows the timing marks, so have a search for that.
I dont live too far from you so if you get realy stuck, let me know. I usualy check the forums once a day.
I wont bother describing the whole procedure as you said your good with spanners, but theres a few things that could have sped things up if i had known beforehand:-
Take the tensioner off once the old belt is off. use a g-clamp to compress it again and insert a small allen key in the small hole it has to keep it compressed, then re-fit it.
when all the timing marks are lined up, the passenger side cam valve springs will be compressed. so when you fit the new belt, line up the drivers side cam marks and the crank first. for the passenger side cams you will need 2 wrenches to hold them in the right position while you put the belt on.
you dont need to take the rad out, although that will give you more room to work. i got away with just removing the radiator fans.
EDIT:-
Found the timing marks diagram here
http://forums.sidc.co.uk/lofiversion...p?t136414.html