I think if I were you I'd have the following tables:
1. Students (with the contact information you mentioned)
2. Leads, where each record will be linked to a record from Students, and a Student record might be linked to multple Leads records
- This table will contain the type of service and the stages details
3. Tutors
4. Timesheets
5. Interactions
- Each record represents a conversation / interaction
5. Optional: Courses
- A list of finalized leads that you would link the "Timesheets" records to. You could also keep this in the "Leads" table, but in my head I like the separation of a "Leads" table with details surrounding that, and a table with details for finalized courses
And they'd all be linked to each other as needed
I'm not familiar with your workflow though, and so it's highly likely that the suggestions above might not work. Let me know where you can see some issues and I can see how stuff can be changed up
You may want to check out the Airtable Universe / Templates to get some inspiration as well