Neither the metal detectors nor the full body scanners currently used in UK airports are designed to measure or detect body temperature. However, the infrared camera systems designed to do this are fairly simple to install and are known to be installed at various airports around the world to catch people with fever. At a much simpler level, the same type of contactless technology is also used in portable thermometers.
For the moment, this mainly targets travelers from high risk areas (i.e. mainland China). Since the known cases in the UK are still extremely rare, it is likely that you would be recognized as having a high probability of having another virus (they are quite common after all). That said, the situation is likely to change, so keep up with the news and take into account the concerns of your traveling companions (for example, bring handkerchiefs and hand sanitizer)