What to do about gap between tile and tub

This is my first shower tiling project and the tub was not level at all. To make sure my tiles were level I left a gap between the first row and the tub on one side (see picture). The gap is 1/2” at its widest. I’m wondering what you would suggest for finishing this project up. Should I attempt to simply fill the gap with white caulk or should I buy some sort of cover?

I won’t re-do this now but for the future should I have done this project differently? Perhaps cut my first row on an angle and left it closer to the top of the tub?