yes you can you can get a travel card to cover all buses but why do you want to take buses ? as travel by bus in london is so slow why not get an all zones day travel card valid for all tube lines ,docklands light railway,trams, buses and mainline rail services within london these currently cost � 4.80 for further help visit www.tfl.gov.uk where there is even a journey planner to help you navigate your way around london by publis transport