What are these for?
 

Whilst cleaning out the spare wheel well in the tourer I noticed,just to the rear of the spare, are two raised slots welded to the floor, each about an inch long. Are they meant to hold something that I haven't got and do I need whatever it is?

Hiya.

These hold a plastic trim that usually covers the radio tuner etc I think.

No.8 on this diagram courtesy of Rimmer Bros. https://rimmerbros.com/Item--i-GRID001824

Yes, part 8 looks like what's supposed to be there,thank you. if there's no gubbins fitted it won't need it.
But a radio tuner there???My "tuner" is the Symphony radio on the dash!

If your car is fitted with the high line system with the telly & sat nav then the “head unit” is simply a control panel/tv screen & the tuner is a big metal box in the spare wheel well