The Guardian reported under the headline "Brexit: Gove refuses to rule out ignoring any law passed to stop no deal":
Michael Gove has repeatedly refused to rule out the possibility that the government could ignore any law passed by parliament to stop a no-deal Brexit
Asked again whether it would be extraordinary for a government not to abide by the law, Gove said: “We will see what the legislation says when it is brought forward.
Concerning extensions, all I found out is the actual article1 reading
- The Treaties shall cease to apply to the State in question from the date of entry into force of the withdrawal agreement or, failing that, two years after the notification referred to in paragraph 2, unless the European Council, in agreement with the Member State concerned, unanimously decides to extend this period.
doesn't specify how extensions are requested, in fact, it doesn't even say anything about a request, just "in agreement with the Member State".
So, the final question:
If the parliament were to pass legislation mandating extension and the government refuses to ask the European Council, can one of these happen:
- the EU just says: "Well, parliament said it, so the UK want to extend, we'll decide if we want to as well"
- parliament (possibly through some representative e.g. speaker) decides to ask themselves
Please don't question if practically the Council could agree internally at short notice, just assume it could happen.
If you want, I'd be happy to see information on whether such an extension without government involvement would practically work, although that is not the primary question.
1 link doesn't go to the treaty, but European Parliament research (including article 50 on page 2) because it provides context and further reading in case anyone is interested.