I confess I didn't see Lisa Nandy on Peston last night, but for me she's still wrong, sadly, for all that she says that she gets it. That she's prepared to vote for Revoke lets the cat out of the bag.
Her view that Parliament must have an alternative instruction I would hope is just clumsy wording on her part. Parliament doesn't get to instruct the government of the day, it just doesn't, it can give its support to a motion (a majority vote for it), or withhold that support (i.e. failing to secure a majority).
What Parliament must have shown before Oct 2019 is a clearly expressed will for what alternative to "No Deal" it will support. Parliament has been asked this question on 4? occasions and has withheld that support each time from the government's proposal and any other one.