1) Invoke article 50 (someone, anyone)
2) Start discussions with EU
That's the plan. The point of the 2 year timeline is to figure out everything else during that period. Someone just needs to start the whole thing. You can't know all the details beforehand.
It's really not possible to have more of a "plan" for something as unprecendented as this. Even ignoring the lies, The Leave campaing was only able to lay out some possibilities of what will happen, not any guarantees. So go on with it and see it through.
There's something called "preparation"...I don't build a house without knowing which builders to call when I decide to build it, how many rooms I want in my house and how much my budget is.
We don't even have enough negotiators in Whitehall to cover the basics in 2yrs; in a BASIC plan for Brexit leave should have set out how they'd negotiate a deal.
They had no plan because they never expected to win.