The deal has been criticised by both eurosceptics and europhiles among her own Conservative Party lawmakers.
"There is an alternative to Theresa May's bad deal and no deal".
Brexiteers have accused the government of betraying the 2016 referendum, as the deal could see the United Kingdom locked in the EU customs union long after the article 50 deadline.
"What is being presented to the public as a sensible compromise Brexit deal, a 52/48 Brexit as some call it, will not bring closure or heal the divisions of Brexit", he said.
The initiative underlines the ire felt in Scotland, which voted to remain in the European Union at a 2016 referendum, over May's plan, which several parties say was negotiated without any attempt to bring them on board. Since then, it has been more and more hard to agree on bigger political issues.
Meanwhile a multitude of other groups and parties are continuing to sound off they should also be allowed to take part, with campaigners for a second referendum even saying they were complaining to Ofcom.
We would question whether the current proposals - which do not in our view meet the requirements under Ofcom for due impartiality, nor ensure that an appropriately wide range of views are represented and given due weight in the debate (Ofcom 5.5 and 5.12 and 5.13) - are in line with those guidelines.
In his speech he is also due to make an appeal for unity and a healing of political divisions over the referendum result, adding: "In politics we can not always have the luxury of doing what we want for ourselves, but we have an abiding duty to do what is right for our country".
May warned that the country would not prosper if politicians did not unite around her plan, and said rebel Tory MPs would leave Britain divided if they went against her in the upcoming meaningful vote.
On Thursday, the Bank of England (BoE) warned that such an eventuality could drag the United Kingdom into a recession and cause GDP to fall by up to eight percent, echoing countless other warnings about Britain crashing out of the EU. The only group which will not sign the motion is the Scottish Conservatives.
She said: "Councils across Scotland are facing huge cuts and the last thing we need is Brexit harming our economy and leading to further austerity, putting more valued services at risk".
Dr Fox, who insisted that Mrs May was "changing the public mood", appeared to suggest that some of his Cabinet colleagues may still vote against the PM's Brexit deal.
In a piece for The Telegraph, the Tory Brexiteer listed key points in May's deal which he says contradict "clear policy", warning that a loss of respect for British institutions could lead to a a rise in populist movements seen across Europe.
"I think every MP needs to consider the importance of delivering on the Brexit vote together with the importance of doing that in a way that is good for their constituents, that protects their constituents' jobs and their livelihoods for the future".