Although the Government is reviewing the legislation around electric scooters, it's not actually legal to ride them in the UK yet, whether that's on the pavement or in the road.
UK law currently states that you cannot ride it on the pavement, in the road or even in a cycle lane. In fact, the only place you will be able to scoot around on one is on private land.
Sadly, the 1835 Highways Act restricts the use of Personal Light Electric Vehicles (PLEV) to private land in the UK.
Electric scooters are classified as a carriage and the 183-year-old UK law bans carriages from public footways. It is deemed illegal for the following:
"If any person shall wilfully ride upon any footpath or causeway by the side of any road made or set apart for the use or accommodation of foot passengers; or shall wilfully lead or drive any horse, ass, sheep, mule, swine, or cattle or carriage of any description, or any truck or sledge, upon any such footpath or causeway; or shall tether any horse, ass, mule, swine, or cattle, on any highway, so as to suffer or permit the tethered animal to be thereon."
You cannot ride in the road either as two-wheeled electric scooters are not classified as road worthy by the DVLA.
So, you can buy a Xiaomi Mi Electric Scooter - or any equivalent vehicle - but you can't ride it in the UK. Not legally, at least. Sorry.