You cannot save a meeting until you have meeting types set in the system. We usually set your system up with preset standards, but your school or MAT may have chosen to override this.
To customise your meeting types, go to Meeting Types in the Administration section. You should make your titles general rather than specific ('Behaviour Review', not 'Meeting with George's Mum Regarding Behaviour') because in the future you'll be able to see these meeting formats in your data. The clearer it is what kinds of meeting you're holding, the more you can track and evidence your practice.