My two pennies worth from my experience in the 'sandpit(s)'
You are going to meet a lot of people when you get out there who have just recently become experts in all financial matters. A high salary does not equate to financial acumen. Currency trading 'funds', Crypto 'funds', Teak forest Plantations in Columbia, ostrich farming in NZ the list of fabulous schemes with stupendous returns is mind boggling and they are waiting for fresh blood all the time. You have been warned!
Why make life so complicated? If you have a house in the UK pay it off. If you want to be cautious (yes I know inflation is rampant) put the first 50K in Premium bonds. I wouldn't leave to much money in Saudi and if you ever find yourself taking money out of the UK then you are most definitely doing it wrong.
Get some time under your belt out there before doing anything that has risk attached to it. That includes shares etc Start saving from Day 1 - 12months will come and go in a flash, you may have had a nice holiday and a fab Mustang car but that is not why you are there.
Enjoy, I made the most of my 5 years in the MidEast and would do it again.
I could go on..... Good luck!
As a one time long term expat in Hong Kong I too have seen everything you write about and there is a lot of good advice there. However, you say 'That is not why you are there' . I am not advocating a fab Mustang car but a good holiday or three? Most definitely yes. I had 23 years in Hong Kong and in that time I saw a number of expat couples who were there for one or two reasons only, usually related to saving money, such as paying off their mortgage and so on. On a three year contract, they returned directly to the UK maybe twice in that time (fare paid by the employer of course) and took part in very little of the socialising and general 'life' of the average expat. Our priorities are all different of course but that is no way for people to live who have been presented with the opportunity of experiencing a different lifestyle, to travel and experience different cultures. I felt quite sorry for them.