My 18 month old is in the baby room at Bringing Up Baby (just south of Goldhawk road) and she absolutely loves it there. She has been going part time since 8.5 months and her key worker is like her second mummy.
We've just decided to send our DS to Monkey Puzzle, behind Brook Green. We did visit Bringing Up Baby, but we felt like Monkey Puzzle was simply amazing. Lots of natural daylight, very switched on manager, emphasis on cleanliness (can't go in with shoes). Having said that I've heard good things about Bringing Up Baby.