Regarding futurelearn NanKate, there's no catch. You can access the courses for free, but if you want to do the test questions ( not all courses have these), want certificates of participation or to keep the course on your file indefinitely, then you have to pay for this, but if you are happy to do the course for the length it runs for plus a couple of extra weeks to allow you to finish it, then it is free. I recommend you google futurelearn - it will explain it more clearly than I probably am. I've done quite a lot of them and found them very good indeed. When I first started there was no charge except for the certificates, but they changed this last year which is a shame, really.