Having gone through all the paperwork that came with the car; it looks like it should have the Park Heat option (shown on build info, and code/info thing pictured), but I didn't get a remote with the car, and the menu screen in the car doesn't list the correct options I don't think?

Also... while I was rummaging in the boot looking for clues I found this mystery plug: any ideas - or is nothing to do with a Range Rover at all?!

Click image to enlarge

Click image to enlarge

Click image to enlarge

What are you expecting to see in the screen menu? That’s to set it to come on at a certain time. If it’s cold it should heat, if it’s warm it will vent.

The remote was an extra to do it from the house etc....

Very rare to be fitted to a Petrol car.

 2011 Range Rover Vogue SE 4.4 TDV8

Previous cars :
2003 Range Rover Vogue TD6
1999 Discovery Td5 ES
1995 BMW M5 3.8 6 speed
1992 Range Rover 3.9 Efi Vogue
1992 BMW M5 3.8
1988 BMW 735i SE
1989 Ford Sierra XR4x4 2.9i
1981 Ford Fiesta Supersport

Ah I see - having owned BMW's with similar options on screen before (which just ventilate) I was expecting an extra 'Park Heat' option to show on screen.
Re. Remote I found wiring in the boot locker labelled Webasto - and think the paperwork with the car mentions remote; so will try and get one from eBay and pair it up; although from scrolling old posts here I gather the FBH can be temperamental so if it's not been used for a while maybe it will need servicing.

I went from a 2003 to a 2011 car, so missed that era, but I imagine operation was the same. I can’t help with the relay you found, no idea.

If you have the FBH there will be a little exhaust in the passenger front wheel arch, down near the mudflap area.

The heater is under the battery and you can see it if you peek behind the wheel arch liner. You should hear it running when it’s on. You could always set it to come on using the screen when it’s cold, and go out and see if you can hear it....

I think if it’s not fitted, the blowers will just come on, but as you have seen paperwork and something in the boot, you may be lucky.... 2011 Range Rover Vogue SE 4.4 TDV8

Previous cars :
2003 Range Rover Vogue TD6
1999 Discovery Td5 ES
1995 BMW M5 3.8 6 speed
1992 Range Rover 3.9 Efi Vogue
1992 BMW M5 3.8
1988 BMW 735i SE
1989 Ford Sierra XR4x4 2.9i
1981 Ford Fiesta Supersport