Once you have your Google Tag Manager account set up to your liking, installing it on your web booking page couldn't be easier.
In Caterbook, navigate to the web booking template editor (Settings / Property / Booking template), scroll down to the Scripts and URLs section, and check the box to Enable Google Tag Manager. This will reveal two text entry boxes - one for your Tag Manager container ID and one for your optional custom booking confirmation page:
A custom confirmation page would replace the regular Caterbook confirmation screen and allow you to track the customer journey right through to conversion. This page will return the booking details such as reference number, arrival/departure dates and booking value in the URL and will allow you to parse this information in Javascript or similar and display it on the page. An example of the attribute-value pairs in this querystring would be as follows:
https://hotelqueste.co.uk/success.html?bookingID=13139&arrival=01/04/2020&departure=02/04/2020&value=60
As you can see here, we have the bookingID element, showing the property booking reference, the arrival and departure date elements in the format of DD/MM/YYYY, and finally the value element which represents the total booking value, and would be important when tracking conversions.