Iris certainly exists in the UK and is very easy to sign-up for. Its only at certain airports though (London ones are LHR and LGW, but I know there's other UK ones too). I don't know the specific rules for eligibility, but signing up is free even for a USA citizen (UK work permit holder) like myself and my wife. Sadly, its only saved us time once, but that one time was probably a good hour or two of time, so I'd say it was worth it. If you search IRIS and UK on Google, I'm sure you'll turn up all the rules and stuff.