Have a look at Maplin site. There is a very nice one XM20W capable of 3 amps. Any decent 240/12volt power supply capable of at least 2.5Amps would be suitable. Make sure the polarity of the output plug is the same as the original.
OnePlus 5 review
Best of the Grad Shows 2017: UAL Central Saint Martins
MacBook Pro 15-inch (2017) review
Comment connecter un MacBook à une TV ?