anything better than RX 480 under £190?

Short answer, no.

The RX 480's closest competitor, Nvidia's GTX 1060, has no significant advantage and costs more money. The only other option would be to peruse the used market. You could probably pick up a GTX 970 or 780 Ti for less money which would offer similar/better performance, but I see little advantage to going for the outdated architecture.