Ministers will meet on Tuesday to sign off on the formal trade mandate document which will frame Britain's negotiating aims, before it is published on Thursday.
"The UK has made clear a number of times, and will reiterate, its desire for a Canada-style deal," Downing Street said in a statement.
The EU-Canada deal, which came into force provisionally in 2017, removes most tariffs on goods traded between the two countries but does little to facilitate trade in financial services, which are very important for the UK economy.
EU chief negotiator Michel Barnier has said Britain cannot have such a deal free from the bloc's rules and French president Emmanuel Macron said earlier on Saturday it was not clear whether an agreement can be reached, as Johnson wants, by the end of the year.
Johnson's office said there were not expected to be any surprises in the mandate document, which aims for a future relationship based on friendly cooperation between sovereign equals.
British ministers were united in their objectives, it said, adding: "this is in contrast to the process of agreeing the EU's mandate, which so far looks to be hamstrung by indecision and delay due to the competing interests of different member states."
The EU had planned to have its mandate pinned down by Feb. 11 it said, noting that deadline had now passed and that EU countries were now locked in debate over how to agree the EU budget for the next seven years.
The first round of formal trade talks will take place in Brussels starting on March 2, with the British side led by its chief negotiator David Frost.
(Reporting by Stephen Addison)