The "further measures", she said, would be set out before the vote on January 15.
But the authorities have been under discussion about using the site over the last two years, DfT confirmed.
On the other side of the Tory divide, pro-EU veteran Ken Clarke said May's deal - which he would be prepared to support - is "dying", and he would be "amazed" if the mood of MPs had changed over the Christmas break.
Meanwhile, Taoiseach Leo Varadkar said over the weekend that while it would be in Ireland's interests to see the withdrawal agreement accepted, ultimately, it is a decision for the British parliament at Westminster.
A government source conceded these may not be secured before MPs resume debating the Brexit deal on Wednesday.
Mr Harrington, a minister in the business department, told Newsnight he was confident that Britain would leave the European Union with a deal as the stark reality facing the United Kingdom became clear.
Reports this weekend suggest that Downing Street are planning to put the deal before parliament up to 30 times in an attempt to bludgeon MPs into backing it in order to prevent a no-deal Brexit.
"Peeling off five of 10 Conservative Party MPs is neither here nor there, but if you get the DUP in line, May will give lots of parliamentarians an excuse to say, 'Well, OK, if they're happy with it I can't really justify going around moaning about the Irish backstop'".
A no-deal Brexit is one where the United Kingdom leaves the European Union but without any agreed arrangements covering things like how trade or travel will work in the future.
The UK's central bank has warned that Britain's gross domestic product could shrink by up to eight percent in such a scenario.
May has little more than a week to rescue her Brexit plan.
"The closer we get to 29 March without a deal, the more assets will be transferred and headcount hired locally or relocated".
"Leaving without a deal would make continued investment in United Kingdom manufacturing a real challenge for global firms, when they have plants in other European locations".
The survey by polling firm YouGov showed that if a referendum were held immediately, 46 per cent would vote to remain, 39 per cent would vote to leave, and the rest either did not know, would not vote, or refused to answer the question. Without taking those voters into account, the poll would split 54-46 in favor of remaining.
The Prime Minister also reaffirmed her opposition to a second referendum, claiming that this would be "disrespecting" people who voted for Brexit.
The government will on Tuesday launch a new radio and social media advertising campaign created to prepare Britons for the full impact of no deal.
"It's very hard to achieve - there isn't a majority in parliament for it ..."
However, the parties own policy is increasing mired in uncertainty with Jeremy Corbyn under increasing pressure to back a second referendum in the event the party fail.