Which snow flocks have you seen so far? I haven't tried
GW's white texture paint, but I imagine like most paints it's going to have the problem of not having the fine grain, shiny/sparkly finish and slight translucency that makes something look like snow.
I like Woodland Scenics Soft Flake Snow and Microballoons for doing snow. They give different effects, so it depends what you're going for I guess.
There's a lot of interesting articles out there on modelling snow. For example....
http://www.009.cd2.com/members/how_to/snow.htm http://sproketsmallworld.blogspot.com.au/2011/11/know-your-snow.html http://hakomike.blogspot.com.au/2014/08/snow-basing-materials-reference.html You do have to experiment, because it's hard to tell from photos what is good and what is bad, and it will vary depending on what you want it to look like in the end.
I prefer using a "water effects" like that from secret weapon rather than using PVA glue because PVA isn't the most stable substance, it can yellow and/or cloud over time (depends how hot and humid it gets where you live).