If you've never had a mammogram, there's a simple way you can approximate the experience at home. You'll need two hard sheets of perspex, a stranger, and a vice.
Have the stranger (preferably with very cold hands) push and prod your breast and place it between the sheets of perspex. Then place breast and perspex sheets into the vice, and tighten to the point where you are just short of passing out from the pain. Then hold your breath for 20 seconds.
Loosen the vice, and have the stranger rearrange your breast so the perspex is on both sides of it from another angle. Then re-clamp in the vice as before and hold your breath.
Repeat the whole process with the other breast.
The whole thing was over in less than half an hour. Now the x-rays from today will go to a BreastScreen doctor, who will look for any abnormalities, and compare them to my x-rays from two years ago. I'll get a letter in a couple of weeks with a result and so will my doctor. Unless there's something wrong, then I'll get a phone call to come in. I don't expect the phone call - there's no lumps or bumps or anything else I can see or feel. (Although, of course, the mammogram can pick up things too small to be seen or felt.)
A mammogram is far from pleasant. But I've known lots of people whose lives have been damaged for ever by breast cancer, a mammogram to detect it in the earliest phases is worth the unpleasantness.