There is still some hope yet for BRExit happening at 11pm today GMT. The thing is, we're unlikely to know about it until next week (Monday) when a case hits the High Court.
May acted illegally in sending out a letter to the EU formally extending the leaving date to Apr 12th, BEFORE the necessary legislation was passed by the two houses. This might now be a moot point, as it was rushed through yesterday.
However, there is a strong possibility that the SI was the wrong instrument, and what was needed was an Act of Parliament.
I would be overjoyed to see Q post at 11:01 UK time 'congratulations on your freedom'. Can't be said before then, as otherwise it might be stopped.