Is hiv transmitted from barbershops in the uk, should i be concerned? are there cases that have been discovered because of barbershops?

The only possible issue you might be concerned about is the use of a straight razor. Here in the US, I have only seen disposable blades, so no worries. What is used in the UK? Do they use Barbicide for disinfecting grooming tools such as combs and hair-cutting shears? More info here: https://www.hiv.gov/hiv-basics/overview/about-hiv-and-aids/how-is-hiv-transmitted/