There can be no ‘special deals’ between Ireland and the UK
It's important to note the extreme complexity of negotiating trade deals. The current World Trade Organisation negotiations, the Doha round, have been going around for 15 years. Now it's not going anywhere but that just gives an indication of how long these things can take.
The EU-Canada free trade agreement that has recently been concluded took many years and that is considered as a potential model for EU-UK relations.
So these things take a lot of time and there is huge uncertainty around them.