Hi eddyglowe
Guidance here confirms that the notional distribution will be treated as allowable expenditure where it is subject to Income Tax in the hands of the unit holder:
CG57707 - Unit trusts: accumulation units.
In terms of when dividends are liable, this is based on guidance here and they are payable for the amount or value of the dividends paid in the tax year.
If your dividends are paid in 24-25 then this is the year they are reportable. You cannot allocate payments and expenses to a preferred year. You can find out more here
SAIM5020 - Dividends and other company distributions: the charge to tax on UK dividends etc..
Should you wish to discuss the specifics of your case then please do not hesitate to contact us direct.
Thank you