Counting chickens etc
Brexit is not a done deal.
If it was, Article 50 would have invoked already and started the 2 year negotiation window.
The main hurdle, which the polititions are pretending doesn't exist, is that UK cannot negotiate post-EU treaties whilst it is in the EU. Thtat's EU law - all treaty negotion must be done under the UK umbrealla. UK is trying to get special treatment, but Germany for sure will not allow that, to stop others following.
Give it six months to a year, enough time for May to completely lock down the UK with snooper's charter etc, and she'll say that Brexit ain't happenin' old bean, and she'll call a general election. Probably win it too, if the media is handled right between now and then.