I have a 2012 Westminster. It has the t91r receiver but I was missing the controller so bought a t91r controller but can’t get it to pair using the instructions for the t91 online.
Has anyone had any luck with this.

I had the same problem with mine, there is a thread somewhere on forum about this, you need a specific remote as there seems to be more than one T91r . I sent my ebay purchase back.
Rog L322 4,4 TDV8
Freelander 2 sold
Honda Transalp
Sunbeam S7 deluxe (in bits)
Sunbeam S8 (restoring)

my 2012 has "91r" written on the receiver but only works with the T91 remote. 2012 RR Westminster TDV8
2008 Audi S5 4.2 V8
2006 Mazda MX-5 R/C Sport 2.0

Gone...
2007 RR Vogue SE 3.6 TDV8
2005 Ford Focus LX tdci 90
2006 Mazda RX-8
1996 Land Rover Discovery 300tdi
1998 BMW 523i
...

I see I also have a 2012 Westminster so this might be my problem. I’ll try and pick up a t91 remote. I know that they are not as easy to find.

I agree they are hard to find but do come up on a certain auction site from time to time, that's how I obtained mine which was new for £50 a couple of years back. Doesn't have to be landrover T91, the vw and skoda T91 is exactly the same and should work.