I'm going through a similar experience. I'm refreshing up my mathematics from when I did A-level mathematics 10 years ago. I'm looking at the A-level material from my distance learning course, and I *think* I can chip away at it. There is practice check before the course that just checks if my pre-requisite knowledge is good enough. Funnily, I'm not too bad at the algebra, but some of numerical basics I'm just so pragmatically rusty at, like fractions, division, etc. The stuff I've usually got away with calculators day to day. I know it's going to be boring going through these by hand, but I know it'll pay off, and make me that more sharper and hopefully a better mathematician. I don't have a strict time limit, so I'm just working away at the basics so they sink in - about twice a week in 3-4 hour sessions so there is sufficient time between sessions to not make it feel dull.