Crestwood High is getting impossible to get into out of area as is Model Farms so I would steer clear of the "wrong side of Windsor road" for that reason alone, unless you intend to go private for high school which of course is a perfectly valid choice
. As for Kings Langley public it is considered a good school "for the area" aka for Blacktown, and it does have a good reputation for Blacktown but the primary schools in the Hills District have better reputations. I think best house in the worst street is the saying and for around the same money or not too much more I'd be inclined to look for the worst house in the best street i.e. other side of Windsor Road maybe Baulkham Hills/Winston Hills. Of course Castle Hill is great but at the more expensive end, not sure about your budget. I think buying in Seven Hills/Lalor Park is a different story as they are considerably cheaper so may be worth the trade off as you are close to the Hills District but have an extra $200k in your pocket but Kings Langley is the worst of both worlds - wrong postcode and high price tag.
VRPS = Vardy's Road public school which is in Seven Hills. As a PP said Seven Hills has lots of primary schools - Seven Hills, Seven Hills North, Seven Hills West, Bert Oldfield, The Meadows, Vardy's Road are all in Seven Hills, there is also Kings Langley Public and Lalor Park Public and all those schools are in the 2147 postcode so lots of primary schools plus Hills Sports High and Seven Hills High are also in Seven Hills.
Good luck with your search OP