I'm in the US, but I'll share my experience. I've been using a TP-Link Kasa KP125 for monitoring my washer's power for a couple weeks. My washer is a high efficiency front-loader. It never goes over 600 watts, and that's at the END of a high speed spin cycle. My washer motor's speed and direction are electronically controlled, and it doesn't appear to have the high "in rush" currents associated with some types of motors and controls. One of my freezers, for example, has an instantaneous peak wattage of about 1100 watts on startup, and a running power of 130 watts. The peak could be higher...the sampling frequency of the plug may not be fast enough to catch it.
I'm planning to use a Kasa HS110 to permanently monitor my washer. And I'm planning to use a modified HS110 for monitoring other motor-based loads. The HS110 is rated at 1800 watts. I'm planning to open it up and solder a jumper across the relay contacts, which are usually the "weak link" in the electrical chain. This will prevent the plug from ever de-energizing the connected appliance (a good thing for me) and should allow the device to be used for most 110V household loads less than 15 amps (almost all of them here in the US).
I chose this specific plug because it's design makes it easy to do my desired modification. There is/was a UK version of the HS110, but I'm not sure how well it integrates with HE. I'm using a different system for power monitoring.
As an alternative, I think some folks who can't use power monitoring are using vibration sensors to monitor washer and/or dryer cycles. Others have gotten more creative with DIY solutions like this one...
