It isn't just EU trade deals that take several years; trade deals between any blocs or countries usually take years because they are so complex.
Ignorant Leavers like Peter Lilley keep going on about tariffs, which are the least important aspect:
It is non-tariff barriers that will cause the real pain.
In contrast, the well-informed Leaver Christopher Booker was writing in the Telegraph today about
the unnecessay pain that a hard Brexit would cause, compared to a Brexit staying in the EEA:
http://www.telegraph.co.uk/news/2017/03/18/david-davis-leading-britain-elephant-trap/
"What is truly terrifying, as the days tick away to Theresa May’s triggering of Article 50, is how little those in charge have any grasp of what they will be facing....
Davis hoped we might be given an extension of the “electronic, light-touch customs checks” that allow 10,000 of our trucks a day to move goods anywhere in the EU without border controls ...
What he still doesn’t seem have grasped is that the moment we leave the EU (and the European Economic Area) to become a “third country”, we are automatically excluded from this electronic system:
to be faced with all the need for paper documentation and inspection procedures which could soon have lorries backing up from Dover to London and beyond."
.... the rules for veterinary inspection of our exports of live animals and “animal products”, including cheese and eggs,
which would now have to be diverted to an EU “border Inspection Post”.
The nearest, at Dunkirk, is so small that it would require massive expansion, and an army of new inspectors, with trucks waiting days for clearance.
As for the fond belief that, without any deal, we could continue to trade with the EU just “under WTO rules”, those still suggesting this are clearly unaware that
not a single developed country relies just on “WTO rules” to trade
The EU treaty database shows that it alone has no fewer than 880 bilateral trading arrangements with almost every country in the world, including 20 with the US and 67 with China;
all of which we would drop out of by leaving the EU.