You can find out whether your hirer is eligible to drive in Great Britain by using the Government’s online tool here: https://www.gov.uk/driving-nongb-licence.
EU licence holders under 70 years of age, living in the UK for longer than 12 months, who meet all the criteria mentioned above will be covered as standard.
If they have an EU driving license and have been living in the UK for less than 12 months but can supply two proofs, as described above, plus their passport they are covered as standard.
Anything outside of the above must be referred to the insurers.