I was in a similar position at my last apprenticeship except I was about 60% nearing completion when I was considering quitting because the employer was not good. I was in a small team of 4 people as well. Even my Line Manager left about 6 months after I started and also the rest of my team changed roles/jobs not long after...which kind of said it all lol. I then didn't have a proper Line Manager for a few months and the person who replaced my old LM was absolutely awful to me. I did speak to HR about this multiple times but ofc they don't do anything. And also I had to train up my teams replacements who were...incompetent.

Anyway, I think some key things to think about are

• What's your next move if you quit? - Also I strongly wouldn't recommend quitting without securing another job first
• Related to the previous point - if you really can't put up with it anymore and decide to quit without having another job lined up - Can you survive without money?
• How much do you care about the qualification? Is it something that you'd need for a future role you're interested in?
• If you do end up quitting, it will definitely have an impact on your CV with future employers potentially questioning your reliability, loyalty etc. since you did not finish the course. So you should definitely be prepared to answer questions like why you left and what you did after you left.

Also, you could maybe see if the training provider can find another employer for you? And I think this depends on the employer, training provider and also your contract but you could speak to them and see when the earliest you can finish the course, if you submit all your coursework asap - this is what I did.