Hi Owen
When the executor of the will has credited your bank account with the capital and your total savings have gone over £16,000 then your UC claim will end. You can make a new claim when your total savings are less than £16k but you will have lost the UC LCW or UC LCWRA status and you will need to complete what the DWP call the Health Journey.
David
Nothing on this board constitutes legal advice - always consult a professional about specific problems