By Kylie MacLellan

LONDON (Reuters) - Britain is committed to leaving the European Union, a spokeswoman for Prime Minister Theresa May said on Friday, slapping down a suggestion from European Council President Donald Tusk that the country might ultimately change its mind.

Tusk, who will run the Brexit negotiations for Brussels, said on Thursday that Britain might decide not to leave the EU as it will not offer London any softer terms than a damaging "hard Brexit".

"The prime minister has been very clear ... that the British people have made their decision and we are now going to get on with that, with taking the UK out of the EU and on making the most of the opportunities ahead," the spokeswoman said.

She pointed to the fact Tusk had also said that Brexit talks should be approached in good faith.

"That is the sort of spirit the prime minister wants to encourage and foster with other European partners, that we approach this constructively," she added.

"There are opportunities both for the UK and for the EU with the decision to leave and so we now need to come together, work together effectively to agree on a new arrangement, a new relationship that can work in the interests of all of us."

May plans to have held substantive bilateral meetings with all 27 other EU leaders by the time she attends a European Council meeting in mid-December, the spokeswoman added. She has already met 15 since taking office in July.

May will also attend an annual meeting of Britain's ambassadors to the other 27 EU countries in London on Friday to hear their views and to set out the importance of strong bilateral relations with EU partners.

"I expect the prime minister to emphasize the important role that ambassadors have to play in Brexit, helping us to establish a granular picture of their host governments' economic interests, which sectors and major companies have most at stake in the UK economy," the spokeswoman said.

(Additional reporting by Kate Holton; editing by Stephen Addison)