Hi again OP - sorry, only just saw your latest post as I don't check Mumsnet that regularly. Here's what I know about the nurseries I mentioned before. They are in different areas of Enfield, so I've also included the location of each one.
Cedar Park (just off The Ridgeway) - great facilities (huge, semi-rural site with lots of outside space); well-qualified staff and lots of 'extras' (I got the impression that it's quite 'high end' as far as nurseries go!). My friend was impressed with the amount of early phonics/number work they did (so much so that her DD found Reception quite dull in comparison), but this might not suit everybody. Quite expensive, though, and from what my friend says there are a fair number of very wealthy 'WAG'-type mums (Range Rovers, blonde hair extensions etc), but not to the extent that this was a massive issue!
Goldstar (Forty Hill) - according to several friends, has very caring and efficient staff and a calm, nurturing environment . Grounds nowhere near as extensive as Cedar Park (it's in a slightly more urban area and is hemmed in by houses) but does have some outside space. Think there might be a couple of previous threads about it on here if you do a search.
Nursery on the Green (Enfield Chase) - very experienced owner who has recently expanded into larger premises. Has just received an 'Outstanding' Ofsted. Again, excellent and well-qualified staff, and living locally I regularly see the older children out and about in the local area, visiting the library/park etc - always seems very well organised. Friends who have used it very happy with provision.
Might also be worth checking out Bush Hill Park as minsmum suggests - don't know it personally but it's in a nice area.