On 16th May, 2022, a total lunar eclipse will be visible in the UK, when the entire moon will turn red (a blood moon).

In London, Namaz e Ayat will be wajib between 03:27am and 05:07am, when the moon is in the umbral shadow of the Earth

Details on the method of offering Salaatul Ayaat according to the rules of Ayatullah ul-Uzama Syed Sistani (May Allah protect him) can be found here