Monitoring water flow on single pipe

We are going to be installing a Sunamp as part of some work on our house in the UK. I would like to find some way of monitoring the amount of cold water flowing into the unit, as a proxy for how much hot water we are using.

I have seen a number of posts where people do this on their water meter, but few about doing so on a specific pipe inside the home. Any recommended devices for doing this? Want something fairly robust - I can’t have a sensor which might break our hot water down the line!

DAE AS200U-75P Water Meter with Pulse Output

Something like this would do?

I believe it is possible to find for your country…