extending the first time is probably OK, the second time not, it would be between no deal or no brexit.For us to extend A50, as far as I am aware, all the other country's have to agree.
It would only take one of the 27 to vote against and we would be back at no deal.
It could well be that May's deal, No Deal and extending A50 won't command a majority of MPs.And that also fails!.
The assumption that the EU is lining up waiting to give the UK an extension is potentially flawed. While some in the centre eg Junkers, Barnier and Our Leo would be wishing it so, it is NOT a fait accompli. All it requires is one country, out of 27 to stick their oar in and the facade collapses...(great mixing of metaphors there). And there is only One week available, otherwise it becomes illegal.
The problem with a rule based system is that there are rules.
In that case, no brexit may be the only possible answer when we arrive at the eve of 29-March.
It may be the best way out, wait until 2022 GE and re-run the referendum.