I'm fascinated to see this thread pop up since I've long had a few ideas for Extended Universe UKCM uniforms based around the Royal Marines. However I largely kept them to myself as the general consensus in the past appeared to be based around Screen Accuracy and Canon stuff.
Also reading what has been posted by other members so far regarding potential for mistaken identity and Walter Mitty accusations I find myself erring on the side of "don't do it" especially since a good friend of mine is a serving Royal Marines Senior NCO and I would never want to do anything to offend him although I suspect he would probably piss himself rather than BE pissed!
Also this has the potential to become a quite expensive costume to create particularly if your body size/shape is not "standard issue" and with quite limited opportunity to wear it!
Finally the more choice of different costumes there are available the less
uniform we become as a group and thus less identifiable as who we are so on the whole I think this is probably not the best idea. However we are also not dictatorship so if you want to invest the time and money and run the associated risks go ahead.
Now in the spirit of Devils Advocate and because I might try this in 1/6th scale as it's cheaper and less contentious! I would suggest;
Dress Blue Tunic with all trace of Royal Marines removed which raises the question what buttons would be used in place of RM buttons?
RM Shoulder titles can be replaced with UKCM titles, available from Moosh89 on Shapeways I believe.
RM Collar badges replaced with UK Delta pins
OR if individual country identity is required then you could have the delta on one side and national identifier (perhaps Patron Saints cross) pin on the other.
No patches on sleeves except NCO Rank. To me the whole point of British Dress uniforms is they DON'T look like Christmas Trees with patches everywhere. OH yes and any NCO rank to be British Apex DOWN Chevrons!

(If you watched The DaVinci Code I could make a joke about British NCO's being C*&ts not P£$%ks!

)
Wings and ribbons on left breast.
Trousers with Blood Stripes (Would you also allow for the Hadrians Wall crew to wear a kilt as they often do with Service C's?)
Plain White Web Belt with Brass Buckle (like 37 Web style) since I am guessing a UKCM Belt Buckle would be prohibitively expensive. Then again as mentioned earlier if you have the cash and or talent fill your boots and make a UKCM Buckle!
Now we get to a really thorny one and I suspect one which will cause most discussion so I'm not going to express any preferences just lay out some thoughts about Headgear!
I'm pretty confident no-one will want to wear an RM Pith Helmet as worn by the Bootneck Bandsmen and on Ceremonial Occasions.
The Cap Vicky showed is referred to by my friend as the "Milkmans Cap" but does have a suitably smart look.
The beret which Vicky has already expressed a dislike of is rarely worn with Dress Blues, mainly in posed "I just graduated Lympstone" portraits for the family. Also the beret could be a bone of contention with some since a Bootnecks Green Beret is not just a hat but signifies the wearer has passed the Commando Course, trainees at Lympstone wear Navy Blue berets on those occasions requiring one.
Red berets while they may look smart could cause even more trouble in certain quarters than a green one!
Also will there be freedom for the Wall Crew to wear a Glengarrie or Tam O'Shanter if they prefer?
Finally when an approved headgear is chosen you will need a UKCM Lion Cap badge since what would be the point of putting a USCM Eagle on a British uniform? I've wanted one of these for a while anyway!

Well that's my thoughts for now so let the flames begin!

_________________
Cheers
Winch
"Yea though I walk through the valley of the shadow I shall fear no evil for thou art with me. And together we'll kick ANY bugs ASS!"
You know who you are!
