It's been sinking for me recently that I'm the ultimate source of my problem with university. I knew it before, of course, but I was still subconsciously blaming external factors for it, and I never seem to take full accountability of my actions.

I have to note that I still strove to be a bit better than my absolute lowest, and I wouldn't berate myself for the choices to solve my problems that I did take since it's better than doing nothing, but it does feel very liberating to tell myself, "You huge dumbass, do you never learn??" Of course, I do wish this sort of nonchalant assessment of my current circumstances came much sooner. I wish I immediately had the ability to realize my faults without laying extraneous self-blame, since it's absolutely useless at solving things. Heck, I don't even know when I'll revert back to old habits of procrastination (I wish I never would, but I have to be realistic).

I dislike repeatedly going back to my old habits and they make me really miserable afterwards. It's fun when I'm just wasting time, and then I feel the consequences. The realization is as annoying as it is liberating.

all i can tell you is that you are not alone at all. i hope you're able to find a way to break your habits and enjoy the time as much as possible.

Here's two things that helped me overcome bad habits, maybe they will help you too.
1.) Think about the worst case scenario of a future you, one that you desperately don't want to become (a hikkineet, for example) and think about what you have to do to avert that future.
2.) Compile a list of "commandments" to yourself, e.g. "I shall take initiative in the household", in the best case as opposites to perceived negative traits of yourself. Putting such things into writing could help you to motivate yourself to actually following through.
Hopefully this helps a little!

You sound British