One of my heater control bulbs had blown, I phoned my local Mr T for a replacement, they would have to order me one, and would take around a week, cost was just under £10
I did some googling and after some time I came across these on eBay
(https://i.postimg.cc/RFchvmYv/Screenshot-2022-04-06-at-2-36-15-pm.png) (https://postimages.org/)
So bought two and keep one in the glove box, arrived in 3 days and at one third the cost from Mr T
https://www.ebay.co.uk/itm/233818497485
If it's of help to anyone