I have 2 kids, 4 and 2 years old.
My son (4 years old) can converse in excellent English.
So, if you can babysit them for a few evenings, while the missus and I take off to the kino, then it will be "perfect match".
Otherwise, I can also give you some proper lessons in exchange for your babysitting. I was a English tuition teacher during my undergrad days.
HAT
(Singaporean Chinese, but google for our stats in GCE levels English exams results, we beat almost all other countries including UK themselves)
Did I just opened a can of worms?