Hello Darren,
To be honest.....I prefer the 1:144 scale aircraft as these do not overawe the battlefield, and take away from the ground warfare.
There are plenty of 1:100 scale metal, as well as plastic kits available for use.
You could try...
www.aircraftmodels.co.uk
www.hobbylinc.com
www.discounttrainsonline.com
www.diecasthobbies.com
...for online ordering.....
Also some wargame manufacturers do 1:100 scale aircraft.....
www.airwar.freeservers.com
www.quickreactionforce.co.uk
...are a few....
True North Models do a decent range of aircraft, but unfortunately they are temporarily closed this year....