well, i have an IUD (coil) i got in america. and reading up on them here in the uk, they seem to be a bit different technically speaking. so i will just tell you that the insertion of an IUD is very painful, but then again, ive never had kids so i dont know how child birth feels in comparison, probably worse. anyways, the pain is bad but it only lasts for a minute and feels like intense cramping (because of something being put in your cervix). i did experience irregular periods and spotting for a long time (something i was willing to deal with) and also a more intense period pain (sort of the same cramping that came with the insertion, only on a lower level). this lasted about a year, after that everything has been fine. i dont have anymore pain, have normal periods, and dont worry about birth control ever. its nice.
looks like most (if not all) of the coils in the uk work from copper. mine actually doesnt have copper in it, it has a tiny amount of hormones, but ive read up on all sorts of IUDs. its sort of a weird way of doing things but that type of IUD, the copper one, works because of way your body reacts to the copper. aside from acting as an actual cork, the copper builds more mucus around the cervix to prevent sperm from getting in and makes your womb not want any eggs in there because there is copper and eeeee everything is scared of copper in your body apparently. anyways, sounds weird, but it works.