I've been running a colonial marines game using the Alien RPG and it generally works fine.
The vehicle rules are a bit shit. Hopefully the 'evolved edition' (i.e. second edition) will fix some of the issues.
Stress dice are literally the only novelty dice mechanic I've encountered in decades of roleplaying which makes the game better.
The rules on how much equipment you should allow are completely fucking retarded. Like, you can have one of a knife, entrenching tool, signal flares, PDT, sunglasses, or wristwatch, when every single marine should have all of those things. Every rifleman has a motion tracker and only riflemen can have them, even though in Aliens it's the combat technicians (Hicks and Hudson) who have them (at least during deployment). In fact, I don't think any of the characters in Aliens save for Apone, Drake, and Vasquez can reproduce their loadout using the rules as written. Playing Royal Marines bypasses this a bit, since you aren't tied to either the book or the film.

In terms of classic British military stories...
The Falklands campaign in general and Goose Green specifically
The Boer War and Zulu War
WW1, especially Passendale and Gallipoli
Napoleonic Wars (via Sharpe)
Boxer Rebellion
Capture of Gibraltar in 1704