Just a quick update.......
The oils ordered on Sunday arrived today - Yippee!!

And I've finally found the justification to get a Dremel (evil laugh

)- to enlarge that hole for the gearbox level plug with the delicate touch of a dentist.............
So, come the weekend I've decided to change the gearbox oil, once that hole is big enough, and change the axle oil. Opinions differ but 8k miles or 12/18 months is one view, and mine is quite dark. I'll take some pictures (obviously).