I did it! I did my first blind hem and it looked fine! This is something that has always baffled me because of the whole folding it this way and that thing that goes along with it. Until I found this video. It explained the folding bit so well that it made you think - what was I worrying about?
I forgot to take a picture before I gave the skirt back to my Mum (for whom I was altering it) but it really did turn out well. I was pretty chuffed with myself. I did use a blind hem foot which came with the machine and I can see that not having this would make it more difficult as you wouldn't have the little guide that special foot has.
It really has made me happy that I got this done - I've had the skirt there for ages and whilst for much of the time, I was without a machine and therefore unable to do it, I was also a bit nervous when I did have one as I didn't want to mess it up, as it's part of a suit. I unpicked the lining and just did a normal hem on that, as had been done on it originally. I nearly cheated and did a normal hem on the main fabric but I really wanted to learn the technique.
Now I have done it once, I'll hopefully be less intimidated another time.
If this is something you're struggling with, I'd highly recommend you take a look at the video I mention. I watched it at 4am whilst unable to sleep and even got it then, so that must say something about how well she's explained it!