Lenovo's IdeaPad 720S is an all-metal thin-and-light laptop that comes in both 13-inch and 14-inch variants. It offers useful features such as Thunderbolt 3, a fingerprint sensor and up to 14 hours of battery life. However, you may need to go up few notches from the £849 (inc. VAT) starting price to get the features and performance you need.
Lenovo IdeaPad 720S review at ZDNet