How do we decide it though?
Can't be leaving it up to the politicians who will surely push for whatever suits their personal agendas.
True. Although at least the politicians will be wholly accountable and any party that took us out of the EU as a choice would shoulder the consequences... good or bad. If a party took us out and things went very badly, they'd become unelectable.
As things stand if we leave, it was the public's choice. No real accountability if things go badly. An economic downturn also provides the Government with every excuse they could ever want to cut unfancied public services.