Greetings from the US....I figured I would have better luck on this forum based on information I have read.

I am looking to install an aftermarket radio in my '08 RRS (possibly Kenwood). I am looking for a double-din radio, prefer if there is a easy wiring kit so that I only need to remove the existing radio & dont need to mess with removing anything OTHER than the radio itself.

One of the issues here in the states is finding the "fitting kits" / dash kits to go around the radios. I've read that it's easier to find this stuff in the UK. I am not under a 'time crunch', so I do not care if I need to order stuff from the UK.

Does anyone have any ideas or places to look?

Obviously the stock radio is not the best, and the stock GPS is . I was looking at Kenwood because you can get the garmin GPS built into a touch screen double din unit....

Thanks in advance! Cheers!

I own a 2006 RRS, and have installed exactly what you are proposing. I warn you now, this is not a project for a novice, or an installer you don't trust implicitly. Having owned my own Mobile Electronics shop for over a decade, and repairing and parting out more Land Rovers than I care to think about, I figured this project would be possible for me. I was correct, mostly.
The system is truly advanced for a design over ten years old, Harman would have had this ready long before the first RRS went into production, featuring optical data communication between the head unit/amplifier/bluetooth/Nav/TV Tuner/etc.
This removed unwanted interference from the system, but also makes aftermarket devices nearly impossible to integrate. I have attached a smartphone photo, of the "finished" product. I can send more if you PM me. Here is the choice, keep everything stock, or install all new gear. I elected to install all new gear. The Kenwood DNX690HD has it's own Bluetooth microphone, Aux inputs, Navigation Antenna, and wireless remote. The door speakers do not have crossovers, so either replace entirely, or install crossovers at the amp. I installed a four channel amp in the stock amp location, bridging two channels for the stock Subwoofer, and abandoning the rear door speakers. There is just not room for a 5+ channel amp under there. The plastic dash kit was ordered from the UK, Connect2 I think. I was able to adapt the steering wheel controls using a PAC interface, and used a Jaguar radio harness from Metra for the radio harness. In retrospect, the Metra harness only gives you memory, antenna amp turn on, and ground, so it's really not that important. I really enjoy having an aftermarket stereo in a vehicle that few have, and fewer still ever modify. I am still searching for the plastic insert to fill the hole left by the factory NAV screen, which would have bugged me more. Hey, if it was easy, everyone would do it right?
 "There's always a bigger fish"

Qui Gon Jinn, Star Wars Episode 1