Conversion tracking can be useful for finding out which of your adverts are performing well, which ones lead to bookings and the types of these bookings.
For the adverts themselves you should direct traffic to your website, where you will likely drop the initial tracking code. Most advertising platforms allow you to track various parts of the journey so you can track CTR, Leads and Conversion.
To track conversions you will need to trigger some tracking code after the booking is complete. You can do this using the “Redirect After Booking” setting which can be configured separately for each service. This allows you to setup a different conversion page on your website for each service.