Will your relocation package include shipping of personal items?
What about expedited visa renewals if needed (otherwise you are unable to travel while your visa application is pending)?
Will they cover tax equalization?
I’d strong recommend requested a paid session with a financial advisor as well, particularly when it comes to investments as there are a number of hoops you need to jump through re: PFICs.
While you didn’t ask…
what have they offered in terms of your base pay compared to your current salary?
what is the pension (equivalent to 401k) contribution they will be making?
will you be on a UK contract which entitles you to additional employee protections (e.g. notice period)?
Few questions;
While you didn’t ask…