Re: Organising the Techies
Write to your local MP. Suggest they get together with various members of their friends & family of a reasonably wide range of age groups. Get each one to check his smartphone for apps which use encryption. Ask them what their reaction would be if those apps were made illegal. Point out that the likely results would make the Cameron policy the shortest political suicide note in history (your MP should get the reference).
Also point out that criminals, including terrorists, disregard laws. Although the MP's constituents would be affected by such legislation and considerably angered by it the terrorists wouldn't. They'd have sufficient resources to roll their own apps; the strong encryption genie has been out of the bottle for a couple of decades now and it isn't going back, ever. So all that will have been achieved is a large bunch of unhappy voters and a smaller bunch of uninconvenienced terrorists.