Last month I highlighted an interest effort to run a DIY referendum on the TPPA. Voting has opened, and you can vote on it here.
The obvious criticism is that a DIY effort has no legal effect. But neither does a referendum under the Citizens Initiated Referenda Act 1993. What it can do is send a message, and help focus public anger if the government ignores that message. So, go ahead and vote - the worst that can happen is that the government ignores it.