I ran new tires at most of the club races last year. If you really want to be as competitve as possible, you will want new tires to qualify on. Having said that, the last race of the year I ran used MGs with at least 80 laps on them and they worked really well still.
I’ve had good tire wear on used tires but found that I had so many heat cycles, the tires really lost grip. You’ll get a feel for all this as you run more. I just got started last year, and learned as I went and asked a lot of questions.
I look forward to seeing you at the Track.