European leaders have warned Theresa May they will play hardball over Britain's exit from the EU.
The UK will face "hard" negotiations if it wants to make a clean break with the bloc, the French president said as the Prime Minister arrived in Brussels for a summit.
And EU leaders were told to "stand firm" in their talks with Britain as Mrs May watched on.
The PM will attempt to ease the jitters Brexit is causing across the bloc by insisting the UK does not want to damage the EU when it quits. But Francois Hollande issued a firm warning that Britain is facing a rocky ride as he arrived for the European Council.
"I say very firmly, (if) Mrs May wants a hard Brexit, the negotiations will be hard," he said.
And in the first formal meeting the Prime Minister has attended in Brussels as premier, the president of the European Parliament made clear MEPs would not give the UK an easy ride.
Martin Schulz said: "I refuse to imagine a Europe where lorries and hedge funds are free to cross borders but citizens are not."
He added: "An overwhelming majority in the European Parliament expects you to stand firm when designing the EU's future relationship with the UK.
"The fundamental freedoms are inseparable, i.e. no freedom of movement for goods, capital and services, without free movement of persons."
A No 10 source said the meeting was "constructive" and Mrs May had received a "good reception".
Mrs May arrived in Brussels declaring she had "very clear message, which is the UK is leaving the EU but will continue to play a full role until we leave and will be a strong, independent partner after we have left".
She added: "It's in the interests of both the UK and the EU that we continue to work closely together."
The PM has indicated that her priority for a post-Brexit deal is control over immigration, which most observers believe will force the UK out of the Single Market.
Mrs May held informal talks with Estonian prime minister Taavi Rovias and Romanian president Klaus Werner Iohannis.