I'd wait for a bit. I'm a mature student doing the new GCSE Maths and the curriculum is ridiculously stupid. Only 10% would people need to know in general. I think this year or next year they boards will restructure it again, as the Government is still concerned about the failure rate. I'm sure a lot will fail this year due to the adding of A level questions to a GSCE paper.
The only problem being independent is the actual application which is usually done through a tutor and then finding some where to sit the actual exam which is authorised to run them.
Unless you are already up to speed in maths don't do the 1 year fast track, it's impossible (we're doing 3-4 subjects a lesson), go for the 2 year instead.
At the moment the AQA GCSE maths scoring (higher) is as follows: Algebra 30%, Ratio 20%, Geometry 20%, Probability and Statistics 15% and lastly Numbers 15%. In all that only the geometry and numbers maybe used by Joe Blogs, with the rest being specialised to work you would do in A levels, apprenticeship and degrees. Whoever thought the curriculum just didn't think of any one getting a job straight out of school, and presumed everyone would need it for degrees etc.
NB They don't even teach how to do a household budget or even basic accounts. Pretty disgusting as that is one skill ALL adults need.