Probably the only way you're gonna find the barrel is with legwork and patience. Questar would be a start, also check Target Sports and The Shooting Edge. I just had a quick browse around, and 2022 bbls in .357 don't seem all that easy to find compared to 225/6/9 bbls in the States, so you might be looking for a lucky break up here...
As for the holster, your best bet is to figure out what style/brand/colour/magical features you want, then start looking for dealers. (Although sometimes I do that & end up spending next month's rent because I end up chasing something that I have my heart set on...)
(I currently live in a box.)