You will need the correct socket which is a spline one, there is one on the side of the box to fill up which is near the starter and the drain is on the very bottom.
Draper do these quite cheep as i bought one when i had to resort to mole grips on a bora once
http://cgi.ebay.co.uk/Draper-Expert...tZUK_Hand_Tools_Equipment?hash=item20adac0bbb
Just fully synthetic 75/90's will do mate.
http://www.opieoils.co.uk/c-673-75w-90.aspx
Fuchs TITAN SINTOPOID SAE 75W-90 synthetic gear oil is good stuff, as is the motul, and the silkolene depends how much you want to spend. When i done the seals in my box il be filling it with the titan sintopoid.