I think if the UK left and later tried to rejoin then they would have to take the Euro but if they just tear up their resignation they probably won't.
On the budget I saw this
http://www.europarl.europa.eu/news/...plans-show-purpose-but-lack-ambition-say-meps
At this moment in time, it looks like a cliff edge in March, the Tories continue to squabble amongst themselves, time passes very quickly and if they have not come up with some concrete solutions by the end of June, I can only see the UK drift off out of the EU, which is even worse than the scenario envisaged two years ago. At that time if they were to leave they would been expected to have measures in place but they are not prepared at all.
Davis is assuming the transition period is a given, it is far from that at the moment unless they resolve the Irish border problem very quickly.