This is the website that my son is using for his maths at school. It's absolutely superb, and goes right up to A level standard.
It is used by schools in the UK, and is available to anyone... the only problem is the cost (over four hundred pounds a year.)
However... if anyone is on a home schooling network, then could the cost be shared amongst a group of ten or twenty families, making it more affordable? If any of you are home schooling, and have a church, or homeschooling network, this might be a useful resource.
Just to let you know, it really helps NON maths folks like me to keep track of where my son is up to... they have "booster" packs to kick the kids up a grade, plenty of revision, games, etc. The home work is done online, automatically graded, and you can keep track of progress very easily.
If I'd had this when I was at school I'm pretty sure I'd have done far better in maths!
Here's some example lessons for you to peruse:
(The first is foundation level GCSE, the other AS level.)