If you can't get them from your local store, you can buy them direct from http://theplasticsoldiercompany.co.uk/
or from places like maelstrom games http://www.maelstromgames.co.uk/
Maelstrom have good sales now and again, but their PSC range is a bit patchy (though they'd probably get them if you asked).
Ebay is full of them too.
Most have reasonable rates to us in the Southern hemisphere. From all sellers you have to be careful to confirm it's the 20mm/1:72 stuff you want, vs their extensive and similarly packaged 15mm/ 1:100 wargaming range.
PS I have not forgotten the Churchill NA 75 for which you supplied me some spare parts last summer.