Sorry to say this but after having first hand experience with a few UK Umbrella companys its a total can of worms and best work via a non UK agency of which there are many .But the way the UK tax rules are at the moment if you work via a UK based agency you can only be limited company or PAYE . Even if you dont live in the UK and are based out of the UK working via a UK agency means you will be taxed , So if your living in Asia and working in the middle east via a UK agency you will be taxed this is why a few of the larger agencys opened up a office out of the UK .All the other UK agencys will try and palm you off with " Dont worry you can go via our umbrella company " Lets be very clear its the agencys job to find personnel get them offshore and earn them money they will tell you any thing ,Please note if you do work under PAYE your be given a emergency tax code which means they will tax you more and at a later date you may get tax rebate .
Speaking for own experience I found the best way was to only live in the UK for less than 90 days a year for many this may not be possible the other thing I would like to bring to your attention is " Common Reporting Standard " Many of the Banks all over the world have signed up for C.R.S. so if your sending all your earnings to a offshore account , That bank will be reporting that account back to the tax authority of the passport holder , Not all banks have signed up for this but a good 75% have .At the end of the day this was to close the loop hole for people having offshore accounts and not paying tax .
So to answer your question which umbrella company its best not to use one because dont forget the UK tax man can go back 6 or 7 years looking for unpaid taxes .
.
.
