U.K. shares fluctuated on Friday and were set to reach their first weekly advance in a month as mine companies gain was overshadowed by a drop of insurance equities. The benchmark stock index FTSE 100 jumped 2.88 points, less than 0.1%, to 6,591.2 as of 12:57 p.m. London time following a previous jump by 0.7%, while it has risen 0.5% this week.