I'm surprised, I'd got the impression that the stereotype was the other way around.
I've known a few girls who have had the philosophy (that I found very unfair on men) that "all men cheat, it's just a fact of life, get used to it", and all these girls were black or Asian and dated men of their own race, so I assume they'd got this impression from those guys. I got the idea that it's a bit of a culture amongst young black and Asian guys to see women, particularly white women who their parents may not approve of, as meat, especially due to the portrayal of women in hip-hop culture, which is primarily followed by young black people and a lot of young Asian people. (It's not principally a race thing, of course, I've dated three very respectful mixed race guys in my time, also none of them were into hip-hop culture.)
And I'm from the UK too, just to clarify.
Also please... don't use the word coloured. Like the word 'half-caste' a lot of people still use it because they've been brought up using it like it's not a problem, but it gets a lot of people's backs up. After all, you're not pure white and colourless, are you? You're pinky orange.

(Unless you're an albino, perhaps, but you get my point.) Some black and Asian people might not mind, or use it themselves, but the ones who do mind REALLY mind.