The best option for Parliament would for me look like the bobbies showing up at number 10 ASAP after BJ breaks the law, Parliament making a humble address to the Queen on account of the PM being under arrest for breaking the law and if she could please spot for the UK government in certain duties just in case Parliament can't find a new PM and then trigger a vote of no confidence on account of the PM breaking the law the way he did.
This, of course, means none of that is going to happen.
This, of course, means none of that is going to happen.