Yes it's fine.
Look at pictures and you'll see mismatched BD all over the place. Especially on Monty!
Personally I do like to have it matching, but honestly it doesn't matter at all!
Have a squizz at Dad's Army. Mismatched trews all over the place 
Plus cold bleaching finished garments always ends in disaster from my limited experience..
Thank you Gentlemen - I can now sew on my insignia!
You've got nothing to ein, zwei, drei, vier
Well everything fades... My serge is quite light and I thought about dyeing it with a choc brown cold water dye (so hopefully it won't shrink).
Needless say, as its made-to-measure, I bottled it!
Couple of commando questions, I'm doing pretty much the same as Gadge:
-Denison smock, yes/no, 1. pattern or 2. pattern?
-Cap badge for No 4. commando?
-Sten MK2 an impossiblity after D-Day?
-Entrenching tool, yes or no?
Why do you always carry that umbrella?
-Bad memory. Never could remember the password. Knew no Jerry would carry one. Had to prove I was an Englishman, you see.
A bridge too far
Couple of commando questions, I'm doing pretty much the same as Gadge:
-Denison smock, yes/no, 1. pattern or 2. pattern?
Go for a repro 1st pattern, it'll cover more of the war period and allow many more accurate impressions 
-Cap badge for No 4. commando?
I don't know for sure, but I'm guessing it'd just be the standard Commando one seen here (with Kings crown):
-Sten MK2 an impossiblity after D-Day?
I don't see why it would be, the STEN Mk2 was the most common STEN produced, they kept on being issued and used through to the end of the war. The Thompson would be a dead cert for a Commando impression in any theatre/period which they operated. Contrary to the premise of your question, the STEN would be more likely after D-Day, as it was developed by the Brits to replace the M1928 Thompsons the British infantry had been using.
-Entrenching tool, yes or no?
Commandos would usually only take what they definitely needed to travel light, but I'm sure one or two may have carried an e-tool or even a G S spade. You're call, really - but 'no' would be the more common/generic answer.
A Proud Member Of 'Team Spleen!' who play mainly at Gunman Airsoft, Tuddenham, Suffolk.
Couple of commando questions, I'm doing pretty much the same as Gadge:
-Denison smock, yes/no, 1. pattern or 2. pattern?
-Cap badge for No 4. commando?
-Sten MK2 an impossiblity after D-Day?
-Entrenching tool, yes or no?
Personal opinion....
Leave the smock, massively overdone, few commandos had them, BD is far more common... commandos pretty much never had them on D-day.
Cap badge for 4 commando.. they generally didnt wear one.. if they did it was of their own parent regiment... only 2 commando had a unique badge. Army commando (i.e 4 commando) didnt use the RM badge,
Sten MKII is fine
I'd leave the entrenching tool off
"I think we are in rats' alley - Where the dead men lost their bones."
Thanks a lot guys. I think I'll still go for the smock, will use it for post-war impressions aswell, and hell, denison smock is one the coolest pieces of military clothing ever.
Would a jerkin be prefferable to the smock then? Anything else I'm missing?
Why do you always carry that umbrella?
-Bad memory. Never could remember the password. Knew no Jerry would carry one. Had to prove I was an Englishman, you see.
A bridge too far
A jerkin is ifinitely preferebale to a smock.
If you really want to wear a denison do an airborne impression its far more fitting.
Very few commandos got denison smocks and then only very late war (winter of 44).
Before then they were really the property of airborne forces, infantry snipers and senior officers who could 'aquire' one.
Commando kit is one of the few things thats incredibly dependant on theatre and year... stuff worn on the dieppe raid is a lot different from stuff worn during the liberation of Holland.... stuff worn in the med.. different again.
If you want 'generic' commando
BD (pref serge although denims were worn and mixed with serge) , cap comforter, skeleton order webbing, ammo boots or boots SV (good luck getting those...) and anklets... a life vest looks the part too.
"I think we are in rats' alley - Where the dead men lost their bones."
Airborne brings the problem of Sten MK V. No capable modders in Finland and S&S might be a tad expensive with postage. Besides, airborne is so overdone
Might get denims and jerkin instead then, already have the proper BD, hot as hell if temp climbs above 20C.
Why do you always carry that umbrella?
-Bad memory. Never could remember the password. Knew no Jerry would carry one. Had to prove I was an Englishman, you see.
A bridge too far