I think it's worth considering whether or not you are prepared to consent to the test, knowing your personal risk factors. You don't have to act on the medical advice that recommends them, you are free to reject it. Your health is your business, not anybody else's.
If you decide you want to have one, you can think about things to make it easier for you eg. booking an extra long appointment, seeing your GP and asking for anti-anxiety medication for the appointment, going to a specialist service for people who've experienced sexual assault, going to a GUM clinic (if they do smears locally), taking someone with you (or not), wearing long socks/thigh highs and a long, full skirt (if you're trying to take off as few items of clothing as possible/cover as much of your body as possible.
In terms of sensation, I describe it as mildly painful - it's a sharp ache and I can feel my vagina stretching in ways it doesn't normally to accommodate the speculum. [Other people use language differently, and obviously other people experience the sensations differently - I don't find 'uncomfortable' reflects my experience] I prefer the feeling of a [warmed] mental speculum to a plastic one (I might be unusual in this) - with the plastic ones, I feel my muscles contracting trying to push them out vs. the certainty/firmness of the metal that isn't going anywhere. I can talk through having it done.
If I was worried about pain, I might go with taking a friend and making it their job to reinforce me/being a witness, so that if I tell the HCP to stop and they don't there's another person to say "she told you to stop." etc. If you try it and it's too painful, you can ask for nice drugs for another attempt.