From their website:
As the UK’s National Measurement Institute, NPL has always played a leading role in providing training in measurement science – an essential skill for the current and future workforce.
…
NPL e-Learning courses available free of charge, includes modules covering General Measurement science applications, Dimensional Measurement and a range of Specialist Measurement courses across a variety of applications. Course modules provide participants with the opportunity to develop or extend their industry-applicable skills – across metrology, measurement and testing, and calibration in both general and specialist applications.
Other notes:
Original course cost vary, up to £700.
It looks like the completion of some courses grants a certificate issued by EAL Awards (Excellence, Achievement and Learning), a British awarding organisation for engineering-related industries.