The UK high court has just ruled that the government cannot trigger Article 50 without a parliamentary vote, see below:

https://www.judiciary.gov.uk/judgments/r-miller-v-secretary-of-state-for-exiting-the-european-union/

This will be appealed by the pro-Brexit government and we’ll likely have to wait until the new year to find out the result of that. In the meantime, it should be kept in mind that parliament as a whole is very unlikely to vote for a Brexit. At the very least, the vote will only take place once all terms have been clarified, which will be very difficult to do for the government at the moment.