Hi REP
Due to the level of investment income you expect to receive, yes you will now need to complete a tax return. investment income over £10k meets the criteria so if you had this for 22/23 then you will need to do a return for that year.
If it is only from the 23/24 year, you can register up to 5/10/24 to avoid any late penalties -
Self Assessment tax returns
Thank you