Hey guys,
Just been out to have another look. Doesn't look like I'll get access through any holes in the gearbox cover, the only ones there are for the reverse switch and the speedo cable.
Tucked on the left hand side, in line with the bulkhead, looks to be a plug. Getting to it is going to be a nightmare, and then as I can't see any drain plug I guess I'm going to need an extraction pump to get anything out of it.
Oh well, MOT tomorrow so she'll have to wait a bit longer before I change the oil.
Thanks for your replies.
Tony.