LONDON, Oct 24 - Sterling edged up against the dollar towards five-year highs set earlier on Friday after a source said Britain's retail sales data showed a bigger than expected rise in September. A source familiar with the data told that retail sales grew 0.6 percent from the previous month, versus a consensus forecast of 0.4 percent. The official release of the figures was scheduled for 0830 GMT. By 0735 GMT, sterling rose to $1.6966 from $1.6947 just before the news. Sterling was still slightly below a five-year peak above $1.70 which traders said it set earlier in the day.//