The providers of each of these are likely to have different standards and the amount of credits a university or institution accepts will vary depending on where you go - the more ‘prestigious’ uni’s are likely to accept less credits, although its always worthwhile to check.
Ask your NPQML provider how many credits and exactly what part of it is the masters part - with mine it was the final report, but only certain sections, so these had to be a ‘pass’ in order for me to get the credits.
With your PGCE, again the amount of credits and whether they are acceptable will be decided by the place you want to study - although if you feel they are being stingy there are usually policies in place that mean you can appeal (I did and got more awarded.)
Lastly, there are hundreds (probably more) of masters courses and they are not all equal as you might imagine - there are highly respected universities such as UCL (London) who do some cracking education masters which will allow you to combine general education issues and topics with your specialism, or you can go subject specific from the outset and find a masters with a local university that you fancy that will probably have excellent localised talent. Its incredibly important you are passionate about whatever you choose, as its a hard slog, especially if you are a full time teacher. I found it helpful to network face to face and so chose a course that had some weekend teaching at points through the course (usually October and July when its a bit quieter in school)
I did my masters in education and learning at Oxford (St Annes) and found them incredibly supportive and their lecturers are just outstanding in every respect. I’m now at Portsmouth doing my PHD as I felt local was essential with all the reading/books and have found them to be equally as amazing.
You won’t be surprised to hear that there are many books out there (online and to buy) which can give you more support about what is involved etc. I bet your local library can organise an inter-library loan if they don’t have the book there - just ask, its usually a small fee but worth it.
If I can be of any more help please do get in touch, I am no one special in the field of teaching but am passionate about using evidence to advance the teaching profession and underpinning crucial research to enable change and teacher and student development. I think we need a bigger, more evidence informed and much stronger voice and debate as teachers about what knowledge is important and how best to teach it. I also think we need to build bridges between academia and schools who can really help one another in realising our goals. Big talk!