She was speaking in her first television interview of the year
Theresa May has stated that there is no muddled thinking from the government when it comes to Brexit.
In her first TV interview of the year, the British Prime Minister told Sky's Sophy Ridge she will be setting out her plan for Brexit over the coming weeks.
May's remarks came in response to criticism from Ivan Rogers, who resigned as Britain's ambassador to the EU earlier this week.
In an email to civil servants outlining why he had made the decision to resign, Rogers said: "I hope you will continue to challenge ill-founded arguments and muddled thinking, and that you will never be afraid to speak the truth to those in power.
"I hope that you will support each other in those difficult moments where you have to deliver messages that are disagreeable to those who need to hear them."
Mrs May said that the UK needs to question what the right relationship with the EU is, and that 2017 is the year change will happen, following the vote to leave the EU.
"I'm ambitious for what we can get for the UK in terms of our relationship with the European Union, because I also think that's going to be good for the European Union," she said. "Our thinking on this isn't muddled at all.
"Yes, we have been taking time," added Mrs May. "I said we wouldn't trigger Article 50 immediately, some said we should."
Mrs May said no plans had been made in the event of a vote to leave the EU, so it was important for the government to first look at the complexity of the issues.
She also confirmed that Article 50, the beginning of the formal process to leave the EU, will be triggered by the end of March this year.
However, she added that she does not see the decision between trade and immigration during Brexit talks "as a binary issue".
"We will - outside the European Union - be able to have control of immigration and be able to set our rules for people coming to the UK from member states of the European Union. But also, as part of that Brexit deal, we will be working to get the best possible deal in the trading relationship with the European Union.
"Anybody who looks at this question of free movement and trade as a sort of zero sum game is approaching it in the wrong way."