available via the Department for Exiting the EU website - 44 pages pdf.
Chapter 5 of the white paper sets out Procedures for approval and implementation of the withdrawal agreement and framework for the future relationship.
There are two statutory procedures to be followed
under - (1) section 13 of the European Union (Withdrawal) Act 2018 and (2) the Constitutional Reform and Governance Act 2010 (CRAG). If "the deal" survives both processes then the government will be able to proceed to ratifying the Withdrawal Agreement at which point it becomes binding on the UK in international law.
In case anyone is wondering, the European Union Act 2011 was largely repealed on 4 July 2018 and will be completely gone on Exit Day - see this Commencement Order. The 2011 Act, inter alia, imposed a requirement for a referendum to be held under certain circumstances.
The European Union (Withdrawal Agreement) Bill has yet to be introduced to Parliament.
In the present political climate it is unlikely that the Withdrawal Agreement will receive approval from the House of Commons. This can be seen in the debate on Monday 26 November where MPs on all sides expressed unhappiness with the agreement / declaration. The political cogs and wheels are in operation and much might change in the time leading up to the vote which, as things stand, is scheduled for 11 December.