Access to 12v and antenna for GPS

[Sleepy's Old Man]

I plan to install an older style garmin GPS in the bin that holds the sat nav in the SE model. The GPS antenna (looks like a toadstool) I plan to fit into the unused speaker grille on top of dash in centre of windscreen.
The problem is to gain access to 12v power and antenna coax cable. I could try drilling access holed but without knowing what's behind the bin it would be stupid to do so.
How much of the dash pannelling is accessable to a semi-competent mechanic?

[CaverD3]

Pull the facia surround offand you will have a better idea of wht you are doing. You will be better drilling a hole in the bottom corner at the back as you can cover it with the rubber mat if you remove it later.
Power can come from the aux outlet but if you want to connect direct you will need to take out the centre console as well. There is permanent live on the right side of the fuse box.
The GPS airial you can drop a cable down the back of the dash. Haven't dome it myself yet though.
You should find a lot of info on DISCO3.CO.UK - Dedicated to Discovery 3 and LR3 Owners and Enthusiasts (http://www.disco3.co.uk.:D)