If it doesn't matter what the country is IIRC you can still pick up the old Mongrel IDF tank crews (even though the rest of the line is dead).
Empress however said that they were intending to make crews for the Airfix vehicles. I'm not sure if that came to anything, but maybe follow up with them if there's a release date.
If it doesn't matter you could just use preexisting Tamiya or Airfix tank crews with different heads. The issue with those though is that they're to scale with the kits the come with, i.e. a smidge bigger than regular 28mm.
Whatever you do. Depending on what you actually need, yes, you could just slap on a greenstuff flak vest and a different helmet for something passing as a Falklands era Brit. ...Unless you have real rivet counters around your part.