Hi OP, I work in maternity in service user representation and I have tokophobia myself due to past sexual assault so I very much understand where you are coming from.
Please please talk to your midwife so you can come up with a birth plan and write it down. They can also put an alert on your notes so that any professionals who open them are immediately aware of your circumstances.
If your midwife is not supportive, contact the head of Midwives at your local hospital - they usually have at least some Midwives who’ve had extra training or experience in these areas.
You can of course refuse anything. Without your consent they cannot do it, and there are other ways of monitoring your baby which do not involve internal exams. For most women internal exams tell you nothing more than how dilated you are.
However, it’s is important to talk to your midwife about situations where internal exams might be much more important than just checking dilation. I am not a HCP but these could include suspected cord prolapse or early rupture of membranes / leaking fluid. Personally I think it helps to understand what might happen and why, so I think it’s really important to have a frank discussion about it. You could talk about strategies that may help (gas and air, epidural, only female staff, staff being aware of your fears and taking things slowly, avoiding speculums whenever possible etc) if there is an emergency situation - you could of course still refuse but I think it’s important to talk about why they might be needed so you can make an informed choice.
I find speculums excruciating but did have to have one before my emcs - that was the only one I needed.
Whatever happens, it will all be much easier if the staff are aware in advance via your notes and birth plan so you’re not having to explain yourself when vulnerable and in pain.
There is also the issue of birth partners right now - if they know that you cannot tolerate internal exams then they may come up with a different plan for you.
If you’re struggling to be heard, google and see if there’s a local Maternity Voices partnership and contact them to advocate for you if needed, I’ve done similar before for women.