I am 8 months into PhD, I’ve always been a hard worker so got my head down and got lots done in the beginning.
But then I had to wait ages for ethics because of playground politics (the group don’t like my supervisor).
I became really depressed and demotivated.
It seemed like my supervisor didn’t care and now I know why because he is leaving. This made sense as to why I had been ignored to get in such a mess.
He finally helped me come up with a defined project idea/question and outlined a potential new supervisor, who, out of all the group, is the only one I could bare to work with because the others are very rude and unsupportive.

Anyway, I still feel this immense lack of motivation, I feel so down. If I leave I am worried if they ask for the last BBSRC 3monthly grant back (only got paid a month ago). What's going to happen to me? I have been working hard toward this for what feels forever, I define myself by this and it's all gone wrong. I don't know what the best to do is to make myself happy....
Advice much appreciated.

Apologies for bad grammar, I had to cut it short to fit it into 200 words.

My suggestion would be not to leave. You’ve clearly worked very hard up until now, and what has happened re your supervisor clearly isn’t your fault. Don’t let that spoil what you’ve done already, and what you can achieve from now on. If your supervisor wasn’t able to supervise you properly and give you the help that you needed, he shouldn’t have taken you on in the first place.
Are you happy with the project you’ve been set? Do you think you’ll be able to work well with the new supervisor? Remember you don’t need to be the best of friends, as long as he is able to give you guidance when you need it, that's all that matters.

Don’t let all the hard work you’ve already done go to waste just because of a situation that was outwith your control. Is there someone else in the department (not necessarily in your group) that you could talk to about your work, supervisor etc? Maybe you also need to take a break for a while to get away from work and clear your head. This might help you feel more motivated when you get back. Good luck!

Thanks Squiggles,
I am just feeling like I am not cut out for this anymore. Maybe if things had been smoother in the first few months it would have been ok, but now I feel like I can no longer do this. I don't know if I have got it in me to turn it around.

I'm sure you can turn it around. If it's what you really want to do, then keep going and you'll get there eventually. Maybe it'll take a few weeks for you to get settled, but I'm sure you'll make progress if you really want to. I often feel that I'm not cut out for doing a PhD, but I'm sure everyone has thoughts like that sometimes. Ok, you've not had a good start, but don't let other people ruin your chances of doing something you really want to do, and can do!

I am confused. You have a new supervisor and a definite project and position in the dept. So why do you think you should leave? It sounds like you need a couple drinks and a chat, a couple of days away and to come back fresh and ready to tackle your PhD...

" who, out of all the group, is the only one I could bare to work with because the others are very rude and unsupportive. "
hmm, this doesnot sound a very nice environment. if I were you, I may consider leaving for a better one; you know, might be good in the long run.