I need to activate Apple TV on Sky TV

A 6-months free trial offer is available to Sky TV subscribers with Sky Q, Sky Glass, and Sky Stream, who do not currently subscribe to Apple TV+. Using Apple TV+ - Sky Help

To redeem this offer, and link the service to your Apple ID account, visit the Giveaways category in the Sky VIP section of the My Sky app.

Once you have this subscription on your Apple TV account, then this service will be available on any of your devices with the Apple TV app, when signed in with your Apple ID account.