As you may well be aware, there is no opt-out permitted if you are selected for a body scan in the UK (well, you can choose not to fly today, but that's impractical for most people). Therefore, here are some things that may help. Firstly, pick your airport if you can. LHR and MAN have nude-o-scopes at all terminals, and LGW has them at the north terminal only. At LHR and LGW, selection for a scan is done by a couple of guys roaming around after the WTMDs. They only do one person at a time. At MAN it works a bit differently; if you're at lane number 5 in any terminal, the WTMD is followed by a glass box (a bit like the penalty box in the USA). If the right-hand door opens, you're free to pick up your stuff from the X-ray belt and go. If the left-hand door opens, it's a free ticket to backscatter-ville. The airport says that left-hand door will open if you alarm the WTMD or if you are randomly selected. At LHR, therefore, it helps if you keep someone in front of you when you're collecting your items from the X-ray belt. If asked where you are travelling to, you do not have to answer honestly (anecdotal evidence is that people travelling to the USA may be picked more often), and the NOS clerks aren't supposed to ask for your name or passport etc. At MAN, avoid lane 5 if you can. They rope off all the other lanes when it's quiet though, so that's not always viable. The fast-track lanes seem to feed WTMD however. Haven't been through LGW North so can't advise on that. Finally, to my knowledge there are no NOSes at any of the transfer checkpoints at the above airports. Do be aware that if you are connecting from Domestic/Ireland to Domestic/Ireland in LGW, you must transfer landside so this won't save you.