Just gone through the exhibitor list, surprised a few names aren't there, Stafford Vehicle Components supply to the classic, vintage and kitcar owners. They have been at Stoneleigh and all the other shows in the past, not on the list this year. Their warehouse is less than 1/2 mile from the show ground but I'm not sure they're open weekends. They stock everything and are cheaper than the likes of Europa. I've used them extensively when building all my projects. Might give them a heads up to see if they are even aware of the event.
Here is their website
https://www.s-v-c.co.uk/contact-us