Yes, you read that right - earthquakes are measured in the UK, it's just we don't have many big ones to record. Those instruments we do have however, are also capable of detecting seismic events happening 100s or 1000s km away.
The main, and official, body monitoring and recording seismic activity in the UK is the British Geological Survey, their real-time data being accessible here. If you click on a particular seismic station it will bring up the real-time seismic data which is called a seismogram or a seismograph. You may also come across the term "helicorder" and this relates to the old fashed drums that were traced upon to produce a seismogram (see below). Today, most seismographs are digital but still produce these squiggly lines that the old-fashioned drums did (or indeed, still do in some places).
An old-fashioned type seismograph recording drum (source).
So how do you interpret the squiggly lines output by a seismometer? Imagine the drum (above) rotating at, say, once every 15 minutes. During each 15 minute cycle, a trace is made onto the drum and after a complete rotation, the tracing 'pen' moves along the drum, perhaps by 1 cm. In this case, it means that each line represents 15 minutes. So in the example helicoider output below, the "X" marks what was happening at just after 01.19 on 10 June 2021.
An example helicoider output.
In the old-days, seismometer were bulky and expensive and as such, were few and far between. In recent times however, technology has allowed them to become smaller and cheaper, with the advent of the Raspberry Pi computer system even allowing for them to be built at home. The Raspberry Shake (pictured below) provides reliable, real-time seismic information for any location on Earth where it is installed and currently, there are some 1300 of them globally.
A Raspberry Pi
I have placed one of these in central Coventry, UK, and as such, it will accurately monitor seismic activity in England's Midlands. With luck, the machine will also record large events happening further afield (this awaits to be seen!) In normal circumstances however, what you will see when viewing this seismometer's real-time data is a clear difference between daytime (when background vibrations pick up, largely due to traffic) and nighttime (when the city quietens down) signals.
Below is a live view of the seismometer as it 'does its job'. This shows only the last 10 minutes of so but if you're interested in historical data, please drop me a line!