Custom Wordpress booking forms and progress forms

Booking / Consulting forms
Using Bookly Plugin and Gravity forms (open to alternatives and/or ideas)
I will create the forms using Gravity
I need help with the activation / storage / viewing on the information.

Using Booking Plugin Bookly/Saloon and/or alternative.
Current Services: -
Reflexology | Petie\Manicure
(option to display separate booking form depending on service or none if already completed previously)
Service A Service B Service C Service D
Book form A Book form A Book Form D Booking Form A

If User Selects Service A > Booking Form A will display
If User Selects Service D > Booking form A will appear
This will be completed online during/after booking. Can we use checkout to pre-populate existing checkout fields if needed? No need to duplicate data entry.
The rest of the forms will be completed by Shop Assistant: -
At the backend/or shop assistant page I want the shop assistant to: -
Select User > Select form > complete details on form. If previous form completed assigned to user, then pre-populate fields from previous form.