Your 60w (hope it’s 60w !!) bulb will consume a fraction over 10 Kilowatt hours of juice during the week. Too work this out multiply 168 (hours in a week) times 60 (the number of watts) divided by 1,000 (to get to Kilowatt hours). It’s actually 10.08 Kwh.
British Gas’s standard rate for pre-pay electricity is currently 13.32p per Kwh. At that rate the cost of running your 60w light would be £1.34. Ten times that, of course, if it really is a 600w bulb!