Apple identifies a small number of iPhone 8 models with a small manufacturing defect, it looks like those in the UK will be safe
As Apple begins Logic board replacement program for iPhone 8 we provide you with the details. Apple advised the affected units were sold between September 2017 and March 2018 in Australia, China, Hong Kong, India, Japan, Macau, New Zealand, and the U.S.
If your iPhone 8 serial number matches those affected then you can claim a free repair, visit this page to see if your iPhone qualifies.
Apple advised this fault does not affect the iPhone 8 plus or other iPhones.