There are sections in the recent road traffic act (the one that made mobile phone usage whilst driving an offence) which will make jammers/radar detectors illegal, but last I heard those sections had still not been made law. Thats not to say you could not get charged with Perverting the Course of Justice which one fella was, although he had an older 'garage door opener' device which can trigger jam codes on the guns (and he had no garage door to open). So bit of a grey area.
I have had a Laser Pro Park for 2 years and it has only been used once, so paid for itself already imo. Not sure what I will do when they are completely outlawed though.