Ok so I decided that changing the colours one at a time wasn't such a big deal after all and now I have the Mini's "Green" colour scheme as my colour set 2 replacing the terrible brown!
I took apw2607 advice and opened two copies of Navtweak and copied the rom_col_8 colours into rom_col_2 and the rom_col_9 colours into rom_col_3 it didn't take that long and I'm pleased with the results. It just means that I will have to repeat the process for future software upgrades!
This Navtweak program is excellent and replacing the splash logo with it as opposed to the Gif extractor means all TMC warning symbols remain visable.

My Landrover Logo is 37kb and I still have all symbols working!
And...... for surfer_matt I'm sure you can save these warning images to your hard drive with Navtweak.....Just right click the line with the image you want to save and it will automatically name the file as it appears in the navboot. I haven't tried editing one and replacing it but I'm sure this can be achieved.
Thanks as always for everyones input!
Andy.