Recommend ultra-fine (0.01" / 250μm) leaded solder?

[lukego]

I want to buy some 0.01" (250μm) leaded solder in Europe. Since a spool will probably last a lifetime I'm trying to make sure I choose the right one. I'll be soldering using very fine tools (JBC NASE) and with a generous helping of added Amtech tacky flux (unless that turns out to kill these sensitive tips, open question.) I have Kester 44 0.015" already but that feels a little thick for 0201 and below to me.

First I tried to order Kester 44 0.01" but the supplier came back and said the minimum quantity is 25 one-pound spools ($150 each.) Yikes.

Now I'm looking at Kester 285 0.01" on Digi-key which is in stock and available in single quantities. Since this is a "spool for life" situation though I'm just wondering whether the flux in the 285 will significantly less effective than the 44? I'm guessing not in the case where I'm using it with a heavy dose of added Amtech flux anyway, right?

I also wonder idly whether I even need flux core solder in the first place, since I'm always using added flux, but guessing it's important for routine tasks like tinning irons after use and so on.

(I have found a supplier for even finer 200μm solder in Europe for less than $10 at https://eleshop.eu/soldeertin-loodvrij-0-2-mm.html but alas that's lead-free and I'm still debating whether to take that step for assembling my own projects or whether to stick with leaded.)

[wraper]

look at TME, they certainly had several types of solder of this thickness.
EDIT: strange. Just checked them and it looks like they stopped selling all leaded solder altogether with recent website update. Previously they had a pretty decent selection.
EDIT 2: They sell it, but leaded category disappear when Latvian region is selected. They no longer sell 0.25mm leaded anyway though.

[nukie]

I use 0.30mm and 0.35mm routinely in my repair jobs. These are Almit, Multicore and Nihon Superior solder wires. Multicore flux doesn't work very well. But all or them are does not solder as well as a 0.5mm wire because there is too little flux in their core.

Additional flux is always good but you need compatible flux so it does not react with the flux in the core.