It's not something you can put in percentages, but racism exists in the UK. I'm black and I've experienced it.
My brothers have experienced it. Getting stopped by the police because they have nice cars. Though that was when they were younger.
I also find as a black person, that other ethnicities (apart from white/white British) discriminate against us. I've been racially abused by someone of Asian descent...I think they were Indian.
I find there is a tendency to dump anyone who isn't white in the same group and I recall a claim of racism work, whether managers said, but the person being accused is Asian (the complainant was black) and I had to let him know in a professional manner that the two were from different ethnicities and just because they fell under the BAME umbrella, didn't mean it wasn't a valid grievance.
Things have improved in my lifetime and I know my DC don't have the same experience s I did.
I know it still exists in recruitment. Employers can put aside CVs of an Asian or African applicant.
An Asian friend married to a white man experienced this. She shortened her name from Anupam to Ann on her CV.
The recruiting manager openly said they weren't expecting an Asian person from the name on her CV. Then proceeded to ask the occupation of her parents.