So i had the following to hand;
1. jack and axel stands.
2.14mm open ended spanner.
3. Adjustable spanner( i didnt have a large enough socket forbthe drain plug which is about 25mm).
4. Oil catch.
5. Oil hand pump.
6.gear oil 2litres.
7. Locking adjustable wrench

First using the locking adjustable wrench(i didnt get a photo of this) crack the square fill plug shown in the top centre of the photo near the starter motor.

Locking adjustable wrench...invaluablebwhen working with seized square nuts...

Once you cracked the fill plug use an open end 14mm spanner to remove it.

Drain the gearbox by removing the drain plug shown at the bottom of this picture, i think its about 25mm but mine was removed easily with an adjustable wrench.
Refit sump plug and using the hand pump fill the gearbox untill fluid spills from the fill plug.
Then refit fill plug.
A lack of photos for the last part, but i found the opening of the fill nut by far the hardest job.
Hope that helps someone out.. I'll add on the differential when i get that done soon.
Rich