Laser detectors and jamming devices are illegal in the UK and if found out you will get fines and points - GPS detectors are not illegal
This is not strictly true. The possession of such devices is not an offence in itself; however, acting on the information they provide in the case of detectors or wilfully obstructing an officer in the lawful execution of his duties (the jammer) would be offences.
As stated above my experience of detectors - driven cars with them fitted - is that they are worse than useless. They are either so sensitive every petrol station you drive past with automatic doors will have the device going crackers or the sensitivity is so low that they miss a direct hit...
As for jammers, the likely consequences of of using one and getting caught far outweigh a minor speeding offence and, believe me, the police are becoming wise to these devices...
I'll provide a +1 for the pocketgpsworld camera database... it is pretty good but not perfect... In the end, there is no substitute for being very observant especially if you're speeding....