So I passed my viva (with major amendments) on Tuesday. The examiners report arrived and basically I have three big issues I need to correct, but hoping for some advice about the best way to go about it.

I was expecting when the report arrived that there would be a clear list of things I need to revise/ add, but what I have is three pages about why my thesis missed the work of an important contributor in the field.

I have also been asked to justify my methodology, include some more results (basically everything I discounted) and explicitly say how my work contributes to professional practice.

My supervisor suggests I should write to the internal examiner with a plan of what I intend to change and how. Is this a good idea? I kind of just want to get on with it, not wait however long until she says yes (or no).

What happens if she says no? And what happens if she doesn't like my amendments full stop (she didn't seem to like anything I did at my viva)? Do people ever fail to get their doctorate at this point?

I would follow your supervisor's advice. Your examiners are clearly on the ball if you got the report so quickly, so there's no reason why you wouldn't get a quick reply.

Yes you can fail your doctorate if you do not do major corrections to the satisfaction of your examiners. The two cases I know of got M.Phil.s in the end. In both cases neither took the corrections seriously (for different reasons) and made minimal revisions (despite having been given a year, which suggests major changes are needed). If you got major corrections, usually both examiners have to sign off on them, so I imagine your supervisor is suggesting running the changes past the internal because she will have a clear sense of what your external didn't like and won't sign off on as well as her own red lines (and regardless of what impression you got at the viva, your internal has a far stronger investment in getting a successful conclusion for you than your external).

I suspect your supervisor might also be trying to slow you down a bit. My guess is that s/he knows you're hurting and not happy at some of the criticisms and impatient for the whole thing to be over, and wants you to get over that feeling a bit before you start to make the changes, so that you do a good job. Could you perhaps write the letter as suggested and then take a holiday to give yourself time away from the thesis? I think you might feel better then about doing the corrections and do a better job, than you will right now, when it's all a bit raw.

Your supervisor's idea is excellent I was going to suggest you doing an outline of where and how you will address the changes, get that approved so you can be safe in the knowledge that that's the right course of action before proceeding.

I went through a situation (minor amendments) where my examiner initially said no to my changes and in fact sent me an email saying he's shocked that I hadn't taken the corrections seriously (even though I did). I did what your supervisor suggested, my examiner came back, said OK, did the changes and finally got the PhD after an 8 month ordeal. In your case you can avoid all that by sending the outline asap (the reason it took 8 months in my case is because my examiner hated my tone in the thesis and took it "personally or politically" let's just say). You won't go through something like this I assure you.
At this stage failure is out of the question IMHO if you pass you pass but you don't get the doctorate until the examiner's happy with the changes. Examiners eventually will agree they just want you to take the changes seriously and show that you value their points (which initially I perhaps didn't do sufficiently in the view of my examiner). Relax you're Dr. Jellybeanz2 in waiting!

I think it's a good idea to send the internal examiners an outline of your proposed changes, as your supervisor suggested.

After your revision, I'd suggest you tabulate all your revision showing how your corrections respond to the required changes. What I did was to even add a cover letter to thank the examiners for their comments and suggestions (whether or not you agree or disagree with the suggested revision).

In a sense, I felt that my internal examiner was trying to be *difficult*. The comments seem to suggest that I did not do a good job...
The fact is I already had three publications before viva... Even journal reviewers/editors did not question me on these things...

Nevertheless, I decided to take the "negative comments" as an opportunity to improve my thesis as much as possible.
My responses had many, many pages. My attitude was "If you want to play, i will play along".
Somehow the internal examiner did not play with me further. Or maybe i was the one taking it personally? :-)