Working full time and part time

Not sure what to do. I applied to McDonald's as a last resort because I couldn't find any jobs and put full time fully flex because I didn't think I would get a job and then I applied before this to work two days as a bartender at Birmingham pride but the pub said I can do part time friday&saturdays if I want. I think there hours are 10-5 so I could do this after the McDonald's job but because my Mc Store is closed at the moment I don't have a time table or what my hours are going to be and I said fully flex so they could say anything. Then again this pub job could say anything. The pub job is not too confirmed but still I don't know what to do know. I've been looking for bartending work but couldn't find any ( as I looked to young / no experience ) but now I don't want to give up McDonald's ( even though I applied as a last resort ). What to do 🙃

Accept both jobs and as soon as you can ask about how shifts get allocated.

Casual employers like this are usually fairly flexible and if they're not then you're not obligated to take the jobs.