Derek is much more dated here than in the US, like
Eric. I'd expect bearers to be 70+, like my
Derek relative, who's 89. But yup that aside, it's not unattractive: it's an unusual-looking name - can't think of any other popular names ending in ek - and the sound is good.
Derrick is a sort of crane to me and looks wrong as a name.
Derick is slightly better; closer to the original derivation.