Usually the more expensive violins come with a fine-tuner for the E string. It’s not so hard to tune the other strings using the pegs. But to tune the E string, each fraction you change with the pegs has a big impact on the note, so it’s easier with the fine-tuner.
An other reason is that on a quality violin you would use synthetic strings or gut strings. These are too elastic to respond well to fine tuners. Since only the E-string is a steel string, it will respond to the small changes in tension produced with the fine tuner.
For the tuner, you can download an app on your cellphone. I use gStrings, it’s free and works perfect.
Good luck with your violin! Must be fun to be playing again after 15 years!!