Umina can be a great spot but you have to get the tide right. If you have an incoming tide you can have the tide moving in towards Ettalong, a Nor' Easter runs side-offshore (in the opposite direction) with some really flat water and small swells running through it. Sounds like you might be after something a bit larger than what's usually on offer there.
I have sailed it when it works and it is brilliant but again... you have to have a few things come together.
There are a few jet skis around but they stay more to the deeper sections and where the break is a bit churned up. The advantage is that if you haven't sailed there for say 5 years and you get excited and go blasting out too far into the wind shadow of the headland and then find yourself in a tide that's moving you further into the shadow, you might be able to get help (and a tow) from said jet skis.

. That was my most recent experience anyway


. by the time I managed to get a tow and then paddle back to the wind zone, I was stuffed.
I'll still check it out again when the Nor'easters start despite a big false start last Summer