I always read these threads and sympathise....
I know the following is not an option for everyone, due to cost, but traditional smear testing at the GPS is not the ONLY way to test for pre-cancerous cells.
You can buy a private HPV test (e.g. from Superdrug online, for about £48). This is just a vaginal swab you can do at home (i.e. it goes no way near as close to your cervix as the traditional smear test so far less painful).
The swab tests for the presence of certain "High risk" HPV types.
The presence of a high risk HPV is suggestive that your cervical cells may have precancerous changes (so you can then go to the doctor's for further investigation.) Conversely, the absence of an HPV type suggests your cervical cells will very likely be normal putting you at low risk of developing cervical cancer over the next three years...
My understanding is these HPV tests are just as accurate as smears (perhaps slightly more so) and they may come to replace smear tests in due course.
The HPV test is a swab, and not a smear, so there's no need for speculum devices, or the presence of a doctor or nurse to do the test, and hence it can be done by you, at home in your bathroom.
That's just an alternative to be considered if you're too scared or uncomfortable at the doctor's.
I had a very high grade CIN, too, several years ago which was treated with the Lletz procedure and I'm very grateful that it was successful.
I've used a mix of smears and HPV swab tests since then. My doctor's surgery have been happy to let me do that. They've recorded those HPV test results on my file and seem to consider them a perfectly acceptable alternative to a smear test.