I just really want to get a head start because maths worries me, and I'm not highly confident in it, and I really need to do it for the future - I got an A* in GCSE but that was a nightmare for me. I enojy it once I get the hang of it, and some of it is really interesting stuff, so yeah :P
The first unit is tricky but if you make sure you can do stuff like surds, finding line gradients and solving quadratics you will have a good footing for the rest of the year. Also make sure you're mental arithmetic is up to scratch as Core 1 is non calculator - well at least it was on OCR- and you will struggle otherwise.
If you really enjoy maths and are considering taking it further than A- level you will need further maths too at least AS level.