Have you seen this website?
I am currently on holiday in my parent's native country with 3yo DS (who is half asian - half english) I amazed at how many young dual heritage there are here on holiday - 3rd generation; i guess.
(If I've got it right First generations (my parents age) emigrated to the UK, 2nd generation like me were born in the UK and like my siblings and many friends married White British people) and our children 3rd Generation have dual heritage.
I was looking for mixes other than just standard English + something else, and came across the above site. The mixes are just stunning!