Thanks to everyone. You've all mentioned the things that I was thinking about so I feel comfortable with all those possible changes.
Micro: that's a fantastic ref. I wish I'd found that at the start of the month. I was kind of going for a Khal Drogo/Daenerys mood so the fantasy romance sounds good.
Charlotte: Yes, I've been fretting about relative sizes of heads/bodies. It's hard enough with normal anatomy but made-up fictional bodies mess with my head. It's one of the reasons why I always struggle with dragons.
I actually thought that the back horsey legs were the worst but, now that I focus on them, the front ones do need some extra work.
Hobby: I know that you know horses better than me so your advice is much appreciated. Looking back I did have one of those legs straighter in the scribbly sketch and it seems to have bent more and more without me realising.
I think if I straighten that again and leave the bent one resting on a bit of raised ground or a rock then it might look a little more balanced and less crippled.
I shall try out a few of these variations tomorrow. Thanks again.