Hello,
As Arlequin said, I am a regular here.
Here are photos of my collection. The Empress and Airfix British are near the bottom of page 1.
https://www.flickr.com/photos/31905569@N05/I suggest that you do not use the Airfix figures and stay with Empress for British Army and special forces.
Empress have an excellent range and the figures are some of the best that you will ever see.
They are correctly equipped and excellent sculpts.
The range is now quite comprehensive with support weapons and good poses.
The Airfix figures are much less detailed. The guns and radio antenna are quite delicate and will easily break.
Three years ago, the only way to get vehicle crew was to use Airfix, but now Empress even have these.
The Airfix vehicles are detailed plastic kits with lots of parts. They are similar to the Tamiya 1/48 kits.
They are very good but need to be handled carefully.
For special forces, insurgents and clandestine soldiers, have a look at Spectre too. These are also very nice.
With Spectre, I suggest you only buy items that are "in stock" according to the webstore.
Restocks are sporadic so you may have to wait a long time.
Regards
Mick