I have such a tiny disposable income that I don't bother with separate accounts, but fully agree they're a godsend to those who need to budget effectively. I maintain an Excel sheet so I can see where I'm at, with pivot tables to categorise my outgoings - pretty much the same effect. Everyone who budgets needs to know what goes where, what to expect and what can/can't be afforded.
My experience: my fortunes reversed in hideous fashion 20 years ago. I went, at a terrifying speed, from not really having to think about what I was spending to having fuck all to spend on anything. Others are giving you appropriate advice: my contribution's a small but vital mindset change.
With any and all purchases, I first ask myself whether I NEED it or WANT it. This was a bit destabilising at first, as I did literally feel like I needed five different Clarins skincare products every month and organic food, for instance. I'm not a complete idiot, though, so I switched to two supermarket skincare products and mass-produced ingredients. In my case, this kind of basic change knocked about a grand off my monthly spending for an extremely marginal lifestyle difference 😳
So it goes something like:
Do I need moisturiser, food, coffee? Yes.
Does it need to be Clarins, organic, single-source? No.
Good: how to replace them? Shop around, get a kick out of bargain-hunting.
With wants like clothing updates, days out, wines and whatever yours may be, I'll consider whether a cheaper alternative could work and, if so, whether I can afford it. My answer's generally no, it won't work. So I shelve the want (they often go away of their own accord) but still keep half an eye open for stunning bargains, in case I can afford to take advantage and still want the thing.
As you're not remotely skint but developing new skills for your new circumstances, I suspect you'll really enjoy it! Best of luck.