The benchmark FTSE 100 index edged up a couple of points to 7,226.71 compared with the close on Thursday.

Eurozone indices took their lead from a strong showing in Asia, with Frankfurt's DAX 30 index climbing 0.6 percent to 11,492.09 points at the start and the Paris CAC 40 gaining 0.7 percent to 5,334.56 points.

British MPs are set for a momentous third vote Friday on Prime Minister Theresa May's Brexit deal, which could end a months-long political crisis or risk Britain crashing out of the EU in two weeks.

The House of Commons has twice rejected May's withdrawal agreement, both times by large margins, but has been unable to agree on any alternative -- and time is running out.

The pivotal vote takes place on the day Britain was supposed to leave the European Union, until May asked the bloc's leaders last week for a little more time.