Investors are preparing for a key speech about Britain's exit from the European Union from UK Prime Minister Theresa May at 11:45 a.m. GMT. May is expected to signal a "hard Brexit" where Britain leaves the single market.

In other news, British American Tobacco (BTI) agreed to buy the remaining stake of Reynolds American (RAI) . The $49 billion deal will create the world's largest listed tobacco firm. 

The focus is on the currency market, as the pound is hovering around a three-month low ahead of the UK PM's speech.

It is also a key inflation day, as the UK Office for National Statistics is set to publish estimate of consumer price acceleration.