I'd want a federation that didnt cost anything, and didnt interfere with my business. It should not have links with anybody, or actually be run by any persons at all.
Lol joking aside mate, we have been down this road so many times, and every time it hits a dead end.
Problem 1 (most major problem) is that window cleaners themselves just dont care, ad are certainly not willing to pay.
Problem 2 is who would run it? you need dedicated, experienced, able people. But those types are not the slightest bit interested in running a fed, they are too busy doing very well thank you with their own businesses. So you only end up with idiot power hungry numpties who think that being on the board of an association makes them feel important. The result of that is that it fails after a few months when the said numpties realise they are actually numpties and dont want to do it anymore.
Problem 3 MONEY. Who would pay to set it up? The answer is...nobody.
The whole idea is a non-starter (unless you're a power hungry numpty, in which case, go for it)