One more tip
Actually two. First, read, study, and consider what gstamer wrote. He is talking about what your body needs to do to roll well as opposed to hints on what to do to help get your body do what it needs to do. Big difference. Not disparaging others who provided excellent advice. To say he knows what he is talking about is an understatement.
My tip is to rotate your body to make your shoulders as parallel to the hull as possible, crunch up to get your face as close to hull, not the deck, as possible, and stretch arms upwards which will put they easily be out of water. I don’t know how your boat is outfitted or how flexible you are as those are factors since you do need to move easily in the boat to do this. From this position, if you sweep out by unwinding you torso as opposed to moving the paddle with your arms and follow the advice of gstamer, I believe you will roll up no matter what regardless of the paddle angle, etc. is.
Oh.one other thing…people tend to talk about the set up position as the position you get in before you go over. The key is to get set up properly after you are over and before you start to roll.
Who knows how you will be oriented when you get knocked down and need to roll. So focus on getting into the right position after you are over and don’t start the roll until you are.
good instructors
The best instructors teach every student differently. Sounds like you need an instructor who can help you find what works for you. The instructor you were using had one way of doing it (and IMO the hardest way for a sea kayaker). CtoC is the first way I learned too, and it’s amazing how much easier rolling got years later when a really great instructor taught me a handful of different ways to roll up.
Sounds good
You may want to keep your practice sessions very discrete as to how you work on this, and make sure that one doesn't counter the other.
The reason I say this is that I am going thru some out of the blue issues with rolling myself, after having been solid on both sides for a while. But I couldn't get into the pool regularly over the winter and it seems to have left some residue behind of old bad habits.
Sculling tends to put you way towards the back deck, at least until you have it down well enough that you can feel that happening and move your torso back out and more centered on the cockpit. That takes some time to get comfy with.
A sweep to C roll, with a hip snap, tends to have the big moment happening when the blade (and your torso) is closer to about 90 degrees from the boat. So if you have a more fallen back position from sculling in your mind and body memory when you go for that roll...
FWIW, I learned the sweep to C for my right side. I sculled my way into my left side roll, just kept sculling until one night I sculled down on my right, went under the boat and started to scull up on my left but (unplanned) came up in a single stroke. They were different learning processes for my body.