Hello Rory
You’d want to start out with The Events Calendar and Event Tickets. These are the free plugins that are a prerequisite to the other features you want. Event Tickets will provide you with the RSVP functionality.
Community Events will allow for front end submissions.
It sounds as if you may not want or need the features of Events Calendar Pro, but it is worth scanning to see if you’d use any of those, such as recurring events.
Does that help to clarify? Is there anything else I can do to help?
Thanks
Courtney 🙂