Beena Hammond wrote:
Can i use an apple watch with a giff gaff pay as your go network (she has a pay as you go iPhone?)
That depends on what you mean by "use". She cannot use cellular services on the watch through Giff Gaff, as its not a carrier that supports Apple Watches, she can use a regular non-cellular Apple Watch through her paired iPhone though, and the carrier would then not be relevant.
Do I need to buy specifically, cellular too?
Only if you want her to have cellular service, and you are prepared to pay for the Apple watch service and move her number and service to a different carrier that does support cellular Apple Watches.
The Apple Watch will work normally if it is near the iPhone even without cellular service directly on the watch.
click here ➜ Use your Apple Watch without your iPhone nearby - Apple Support
The questions you need to answer are:
Do you need her to have cellular service on the Apple Watch? Or will it be near her iPhone always and can use it for Internet connection, and messaging and call services?
Do you want to pay the extra cellular service fee for the Apple Watch on a supported carrier?