electrician

I live in East London, E16, and have a key controlling 4 lamps (All in series) in my room. I need to add a new pendant lamp, which needs additional wiring (not necessarily inside the ceiling) and would like to control the pendant and those existing lamps independently. No additional keys are available for the new pendant. But I need to turn it on while the existing ones remain off, and vice versa.
I would like to know the approximate cost and your availability for tomorrow, 25th.
Thank you