You need to show the appropriate amount to cover the costs of the proposed visit.
Unlike Schengen visas there is not a specified amount per day - £2k would not come close in my case so you need to satisfy the ECO that the amount is sufficient.
It has been said before that Jomtien wants you to do the first 90 report personally, after returning from abroad. They also required you to have a 'current' TM30 receipt prior to doing 'business' at that office.
A friend's wife in the UK obtained Leave to Remain in October 2021 and that expires on 30 April 2024.
The issue is that they have overlooked the fact that expiry is imminent. The situation is compounded by the fact that the applicant is currently on a 2 month holiday in Thailand.
Is she able to apply for FLR from Thailand?
Whilst this oversight is entirely their responsibility I am surprised that there isn't some sort of 'reminder' from the UK authorities.