"[No Deal] is the default, no permission needed they need a concrete alternative, one that the EU also back. Surprised you struggle to grasp this jim."
As I say, I accept that this is technically true, but:
1. The EU Council doesn't want No Deal.
2. The UK Parliament doesn't want No Deal.
3. The UK electorate almost certainly doesn't want No Deal, as best as it's possible to tell.
As long, therefore, as all three parties don't want this outcome, then they will work to avoid it. As to its being the default: This is true, but there is an emergency EU Council meeting scheduled for April 10th, at which it can be presumed that Theresa May is going to ask for a further extension. It is also fairly likely that, later this week, Parliament will grant permission for it.
It is finally worth noting that the bulk of the EU (Withdrawal) Act 2018 hasn't come into force yet, including Section 1, which repeals the European Communities Act. As far as I can see this is only a matter of the Sec. of State for Brexit specifying a given date, but this hasn't happened yet and morally can only happen once there is consensus on the way forward, which there is not.