Yes, you need to pay for a connection for the watch , you cant use the data you have on your mobile.
This is charged at £5 per month...
Current Phone: Sony XPeria Pro-I and Motorola Razr 5G I also have a Planet Computers Gemini
I work in IT as an Enterprise Messaging and Collaboration Tools Administrator (Office 365, Slack and much much more) and manage hardware both Mobile and Desktop / laptop, my desk is a bit like PC World
-- We are all customers and dont have access to any o2 accounts