British Prime Minister David Cameron and French President Francois Hollande will meet on Monday to discuss Britain's EU renegotiation, ahead of a crunch summit this week.
The talks will take place in Paris at 1800 GMT.
British officials hope a deal can be guaranteed at an EU summit in Brussels on Thursday and Friday.
"We have made progress [on renegotiations], but there's details to be pinned down,” said Cameron’s spokeswoman about the meeting in London.
"Nothing is agreed until everything is agreed," she added.
After the EU summit, if a possible deal is agreed on, it could pave the way for a referendum on whether Britain should leave the 28-member EU or stay in.
British Prime Minister David Cameron also spoke to European Union Chief Donald Tusk on Monday.
Asked after a meeting with French President Hollande in Paris whether he thought a deal was possible at the Brussels summit, Tusk said: "I hope so."
British and EU negotiators have already broadly agreed much of a reform package, but tricky political issues, notably on migration, are still outstanding.
Furthermore, Cameron’s spokeswoman gave some statements about England’s expectations from the meeting.
She said that Britain was seeking "significant and far-reaching reforms."
"There are still details to be pinned down and what matters is that we get the substance right."