You can get these on amazon https://amzn.eu/d/0daEIZUa Or cow and gate ready made bottles with the teats on them x
Would the sterifeed teats work? You can buy them on Amazon, I know my hospital has them to give to parents when they are in with babaies. They have these tests and a few different types of milk so I’m assuming they must for multiple bottles?
I managed to get an itsy guzzler in Asda a couple of weeks ago. Might be worth checking in there x