As that link says, you do not need to routinely carry your driving licence in the UK even if driving. If stopped, you are required to give your name and address and police have the option of giving you a "presenter", a notice that you must turn up at a police station within 7 days with your licence (with some exceptions eg it's been stolen or with the DVLA for changes to be applied). But in my experience it's unusual to be given one of these.