LONDON, July 6, 2018 (News Wires) - The European Union's Brexit negotiator said on Friday that the 27 EU nations discussing the divorce terms with Britain would be willing to adapt their stance if the departing member shifts on key issues. Michel Barnier said Friday: "We are ready, I am ready, to adapt our offer should the UK's red lines change." Britain has said it doesn't want to be part of the EU's unified market and customs union with the remaining member states so it can develop independent trade, economic and social policies once it leaves the EU next year. Barnier says huge obstacles remain as the negotiations on a settlement continue. British Prime Minister Theresa met with her divided Cabinet on Friday to try to hammer out a plan for future trade with the EU. As the British government bickers, European Union leaders are growing impatient and have warned Prime Minister May she must present concrete and "realistic" proposals within weeks if there is to be a deal by the time the UK leaves on March 29, 2019. The bloc has repeatedly warned Britain that it cannot "cherry pick" the benefits of EU membership, such as access to the customs union and single market, without accepting the responsibilities, which included allowing free movement of EU citizens to the UK. EU Brexit negotiator Michel Barnier stressed Friday that Britain can't treat the single market as a "big supermarket." The EU is also demanding certainty on the future of the border between Britain's Northern Ireland and the Republic of Ireland - the UK's only land frontier with an EU member. Britain has promised to maintain an invisible border, free of customs posts and other infrastructure, but have not said how that can be achieved.