haplesshippy, I'd say you've got 2 separate problems going on here -
One is a normal and reasonable anxiety about approaching birth - the other is scanty care and a bafflingly unsupportive MW.
Of course, the latter is going to make your general anxiety worse.
In all honesty, I don't know that you should be thinking about hypnotherapy at this stage as a way of compensating for the poor care you've had so far. If you want to try it because you think you might find some of it useful at this stage, then fine - but calming breathing isn't something to suggest a substitute for a MW refusing to discuss a birth plan with you.
It depends on what kind of a person you are, and how you like to approach things in general. But at this stage, given you are 38 weeks, you might draw up a plan of action, with your partner, to make sure you get the care and info you want.
I would ring your local hospital, find out who the Consultant or Head MW is, and ask for a meeting or a scheduled phone conversation with her. Tell her through no fault of your own, you have missed antenatal classes - that you want to discuss a birth plan, and your community MW has refused to do this - that you want someone to go through your notes with you, as there is info in them that you find worrying, and no one has discussed it with you. Think about any other info you would like to be talked through, that you haven't had the chance to do so far. As others have said, at 38 weeks, you might well want to ask about pain relief options, when to call the labour ward - even what to pack in an overnight bag.
If your partner can help you be assertive, or be assertive themselves, then great. Assertive doesn't mean rude or stressy! It just means being clear and straightforward, and feeling you are entitled to ask questions that are important to you.
You might ask for a tour of the labour ward (some hospitals do them, I think).
I'd say by all means explore anything you might find personally relaxing - but do this alongside addressing the gaps in your care. You shouldn't be in this position at 38 weeks, but as you are, then you can very reasonably ask for help by going 'up' a level to Head MW.