The alternator will still charge without the light working, providing the alt isn't duff, as it will kick in at higher revs and then stay in until stopped, so as a temp just blipping throttle will get it kicked in, but better to have working circuit of course.
You need to establish whether it is the just the bulb/wire to it or if it has stopped charging, connect a metre up before starting engine note reading, start engine then when revved high enough it will kick in and show a higher reading all of a sudden.
Sometimes it is just a crudded up connection on the alt IND terminal, the one where the thin blue wire goes.
tabetha