It's possible a 'no deal brexit' could be taken off the table at some point. Which, in effect, means there can not be a brexit worth it's name.
I don't see how MP's can stop No Deal.
Yes they can have a vote to register their displeasure and maybe this amendment to change the way Parliament works that Dominic Grievance is bringing forward may make it possible for Parliament to change the legislation that we leave on the 29th March.
However, under the terms of Article 50, EU Treaties will cease to apply once the 2 year period is up, ie 29th March. This is EU law which is superior to UK law.
So the only way to avoid No Deal as I see it is to either revoke A50 entirely or to persuade the 27 other EU countries to allow us to extend the A50 period and the difficulty with that is the EU Parliament elections in May.
If you read the act, you'll see that it refers almost exclusively to "Exit Day" rather than any specific date. 29th March is mentioned in Section 20, subsection 2, which is the part of the act that deals with interpretaions of the various phrases. However, Section 20, subsection 3 & 4 give a Minister of State the power to vary the date of "Exit Day".
http://www.legislation.gov.uk/ukpga/2018/16/section/20/enacted#section-20-2
So from the UK side, there is no issue with the government changing the date of "Exit Day" since the legislation already allows for it. AIUI parliament can order the government to do that.
Whether the EU27 agree to extending the Art50 deadline is up to them. Personally I think they will if a second referendum, or some exit deal looks likely. I don't think they will if it looks lie the UK is playing for time and/or just wanting to re-open the May agreement.
It matters not, as the date and time of 23.00 on the 29th March 2019 was enshrined in EU law when we handed in the A50 letter, according to the provisions of Article 50 of the Lisbon Treaty.
EU law is superior in this case so Parliament does not have sovereignty and cannot do as it likes as you always claim.
Sigh, No.
What the European Union (Withdrawal) Act 2018 does is determine the way that the European Communities Act 1972 is repealed (It says that in section 1 of the European Union (Withdrawal) Act 2018) .
http://www.legislation.gov.uk/ukpga/2018/16/section/1/enactedThe European Communities Act 1972 only applies within the UK (and other dependent territories). The UK parliament is and always was free to set any date it wishes for the repeal to take effect. However, treaty obligations meant we had agreed to give 2 years notice, which have now (almost) elapsed.
Parliament can and always could decide on what day EU law ceases to apply within the UK. It could even allow European Law to apply after 29th March - that's the way any Brexit extension will work if it happens. However, without the agreement of the EU27 we loose any say on what those laws are after 29th March.
Extending full participation past 29th March requires the treaty to remain intact. Which means a Minister of state extending "Brexit Day" via Section 20 subsection 4, and the EU27 allowing the extension via Art50(3). Or us unilaterally withdrawing Art50.