Invested with Robinhood UK, do I need to submit self assessment?

I started investing with Robinhood UK and received a Form 1042-S last month. There were 3 codes - 01 (interest), 06 (dividends) and 23 (other income). 06 and 23 have tax withheld, although they are very small amounts. I'm not sure if I need to submit self assessment to declare these foreign income, especially since I'm a high taxpayer (but not high enough to need to file self assessment).