Good morning - i have a p38 petrol.
I am having some trouble with my gearbox. from a standing start the car sometimes does not pull away, it a fraction of a second but its now getting worse so that its noticable, I also find that it sometimes jumps into top gear when cruising - do I have an expensive christmas ahead of me or do I just have to change the gearbox oil???

Always a good place to start. The filters on these things need regular changing (there was an excellent post with pictures on here a few months ago - have a search) It can be done at home if you have the space but shouldn't be too expensive to get done at an indie.

Put it this way, it is the least expensive of the options and needs to be done anyway.

Checking the oil level would be a good start

I'm assuming it's an auto.
Check your fluid level and colour, it should be red.
If it's black then changing it is worth a try.
If it's black and smells burnt then it's box repair time - talk to people with more knowledge about boxes than me - not difficult.
If you change the fluid then don't be half hearted and drop the sump and change the filter as well. I found the most difficult part was convincing my old bones to lie down on the cold ground.