Hi Andyd. I personally used test prep providers to prepare for the CFA. I think one of the best known providers is Schweser. You can check their website at
https://www.schweser.com. I also know about Stalla (
https://www.stalla.com) which is another good test prep provider. I cannot comment on the latter since I did not use it for my preparation although I did see the actual books. I did not find the latter as user friendly as Schweser but that may be more a matter of personal taste. You can also buy the actual AIMR books at
https://www.aimr.org. Some people find it more useful to have the actual books but you don't necessarily have to buy the recommend textbooks. The difference is that if you buy the textbooks (~1200$), you are good for the 3 levels (unless there are new editions coming out) whereas you will have to buy the study notes for each of the level (~299$) if you do it with a test prep provider.
If you have a good finance background already, a test prep provider should be sufficient to make you pass each of the level. You can also check out this website:
https://www.analystforum.com which is an active CFA candidates community where you can post your questions. I am not too impressed with many of the threads on that forum but it is the only one I know of that is CFA related.