Setting up trade agreements is never "quick" Canadas had a Summit with the EU on 18 March 2004 to set up a framework for negotiations with the EU which didn't actually start until 6 May 2009. It wasnt until the 1st of August 2014 that negotiations were concluded. 10+ years that took.
Ok I doubt we would take that long but to get the deal we want to trade etc we will still be giving in to the Freedom of Movement and still be paying into the EU for the pleasure of trading etc. So many negatives and what ifs. Voting for In purely on the basis that I know what I am voting for. Voting out means too much uncertainty. If there was any kind of structure laid out for the out camp, I'd be very interest but until then, Im not.