You can state that you do not wish to have any internal exams. If they give you an internal anyway then its assault.
Lots of PCT's say that women should have VE's when they arrive in hospital and every 4 hours thereafter, and that they should have a VE before they start to push. But as you're not their employee you're under no obligation to abide by their policy.
There are reasons why a VE might be a good idea. If labour doesn't seem to be progressing then a VE might give an idea as to whether dilation is happening quietly or not at all. If you've started pushing (either actively or passively) and there doesn't seem to be any descent then a VE might provide useful information and help resolve the issue before it becomes a problem. But there should always be a clear explanation as to why a VE is recommended, including what information they hope to acquire and how it will be used.
When I had DD1 I didn't have any VE's at all - but I did have the advantage of an IM at home that new me and that was with me for the entire labour, which meant she was able to judge how labour was progressing through observation of me rather than point checking my cervix. With DD2 it was all a bit different as I had to be induced in hospital with gel inserted in the cervix, then a 2nd dose, then checked about 6 hours later, 6 hours after that and once just before 2nd stage.
So after all that, you can plan and insist that you will not have any VE's and (short of getting your committed under the mental health act) there is nothing they can do to force you to have them. But there are a few discrete situations where a VE might yield valuable information - its up to you whether or not you think the information is valuable enough to justify having the VE.
I'd suggest talking to your MW and explaining your position. They ought to be sympathetic and prepared to work with you to make the whole birth as untraumatic as possible. If your MW isn't helpful, talk to the Head of Midwifery at your maternity hospital directly - preferably in writing (its amazing what changes when things are in writing). If you still get nowhere, AIMS should be able to give you advice, or you might want to look into an Independent Midwife - they're not cheap but they tend to be very focused on providing woman centered care.
You might find these phrases by Mary Cronk useful to remember.
I'll caveat now and say that I'm a lay person that takes an interest in pregnancy and birth, having been through it with two very different experiences - and that a lot of it may be UK specific. I hope some of that is useful and pertinent to you in France (assuming I've got that bit right). I'm sorry its bringing back so much trauma and hope the rest of your pregnancy and birth can be more relaxing for you.