Not in 28mm (but admittedly, I've also not really looked). I suppose the old Warzone Imperial trenchers might work (tommy helmets, gasmasks and long coat-like garb) as well (they're cheap, too).
Since I use my (
IG) minis for a tactical cyberpunk-type game as well (like necromunda, but more corps v punks than gang vs gang, but that does happen as well), I like my regular grunt guys to be more modern.
After a bit of digging, I found this lot, but nothing in greatcoat guard.
http://eurekamin.com.au/index.php?cPath=87_126_193.
Eureka miniatures, a local company (for me) who do pretty good work, and have a fantastic customer service policy. Not the exaggerated proportions of
GW, and lacking some detail, but plenty of gamers here have used their stuff.