Ability to sign up for pre-scheduled meeting

I'm just learning Bookings, and I'm grateful for the service that allows clients to book time with me, and know details upfront etc. for individual 1:1 training sessions.

However - I would like to create an open training session that anyone can sign up for. And it doesn't seem like I can set time/date in a service.

As an example, Ideally a client would get to choose from services:

Custom 1:1 60 min session (they pick the time when scheduling)

Custom 1:1 30 min session (they pick the time when scheduling)

Monday at 12pm for group session

Thursday at 10am for group session

Anyway to do this that I'm missing?