The meeting follows an offer last month from Aung San Suu Kyi to cooperate with Myanmar's rulers to get US sanctions lifted.
In the letter to Myanmar's military rulers she also requested a meeting with Western diplomats to discuss the sanctions and understand their positions on the issue.
Speaking to Al Jazeera after the meeting, Andrew Heyn, Britain's ambassador in Yangon, said he had interpreted the meeting as a "fact-finding mission" by Aung San Suu Kyi to get a clear picture of the existing sanctions against Myanmar and their impact.
"She really wanted to understand the facts and the background to the sanctions regime in place," he said.
On the question of Aung San Suu Kyi's health, he said she had appeared in "very good form - particularly considering what she's been through - she was very eloquent and very engaged."
"At the moment we've got some things which are encouraging, but there have been false dawns before"
UK ambassador to Myanmar
Heyn said the meeting had been a positive indication about possible movement towards reconciliation between the military and the opposition, but this was only at the very initial stages.
"At the moment we've got some things which are encouraging, but there have been false dawns before," he said.
Earlier, speaking to reporters in Yangon, Heyn, acting as the European Union's representative in Myanmar, said he had expressed the EU's willingness to "respond positively to any concrete steps toward political reconciliation and genuine democracy."
Aung San Suu Kyi had previously backed sanctions as a tool to pressure the military government to work with her pro-democracy movement.
Her party, the National League for Democracy (NLD) has insisted on concessions from the government if the two sides are to work together – primarily it wants to see the release of all political prisoners.
Last week a court in Yangon rejected Aung San Suu Kyi's appeal against her continued house arrest, upholding her August conviction for sheltering an uninvited American at her home earlier this year.
Her lawyers have said they will not give up and plan to take the case to Myanmar's supreme court within 60 days.