ive got a oil leak on the top of my gearbox. i recently had oil and filter changed by land rover and now i've a leak on the top of the box. land rover are saying 3 hours to take the box out

 

Sounds a bit too coincidental to me. Might be worth a second opinion unless you want to crawl under there and see if you can determine the origin. I'm assuming it's an automatic (because you mentioned filter, we didn't get any manual DII's here). There is a vent line on the top of the trans (actually it's on the left side 3/4 of the way up) that could be leaking, and there's a trans oil cooler pipe that fits into the left side up high as well (almost said drivers side, that would have really confused things in this case). Neither one of those would require trans removal. Ask them specifically what is leaking(rather than the generalized, "the gearbox is leaking"), if they don't know, find another opinion.

 

So, how mechanical are you?
There should only place where the tranny can leak on a 03 and that would be the vent hose.

 

The trans has cooler lines that are under pressure, the 03's don't have an engine oil cooler but they do have a trans cooler. One of the lines is on the bottom forward part of the trans and the other is on the left side 2/3 of the way up on the rear part of the trans. The vent line is just that a vent, while it might drip a bit of oil from the oil mist in it, but it shouldn't have any significant amount of oil in it unless it was overfilled. (which is another possibility in this case)