Do I need medical Ins for a long overdue short break to Italy? I have a current EHI card, will this give me good/free cover?

Agent wants to sell me additional cover but with a under control heart condition & recent brain surgery (to remove benign tumour) the cost is prohibative.

Am I legally required to have this?

I can't find a straight answer online.

I know that I will need travel ins to cover delays lost luggage etc.....

Any advise would be appreciated - thanks.