Quite interesting
On an independence slant, don’t necessarily disregard the IRA - providing you look at the first Irish Republican Army which was the origin of the Free States army, then with Eire and now the Republic of Ireland - now known as the Defence Force
Into the 90s they kept with simple olive green instead of migrating to disruptive camouflage patterns - largely due to the troubles avoiding border confusion with the British army, but have moved onto DPM - but with a different paddyflage colour pallette
(The Rangers went DPM earlier in the 80s)
Now they would be seen in their own variation of multicam ITMP - which has FF embedded in the pattern …. Worth a Google for general interest, but it’s not your target era, you could consider for a later 2020s ScotCam)
In the 90s most army’s had a mix of plain green and camouflage patterns depending on the order of dress for what they were doing. Today the camouflage scheme is typically used for most forms of dress (there is interest in reverting to a barracks dress but MTP dominates all but dress uniform - and if your regimental dress code formally retained the green wooly pully as at the right date then it remains permitted but other regiments / corps it’s MTP with no wooly pully)
Ireland and Scotland have very different histories with England
Both have been subject to historic occupation with brutality, the handling of Catholics and migration (potato famine & the highland clearances being of note)
But they have been on very different levels - it would depend on your alternative history backstory
With a lesser ‘hatred’ level, and geographic position I would feel that an independent Scotland would not have remained neutral for the world wars - not just for the different England / Scotland situation but with close historic ties to France and constant ties with the Scandinavian countries
Scotland was (and still is) essential to the UKs naval strategy, in the 1900s still had a solid ship industry - this declined post war and was reinvested in around the 60s/70s
I could see a period of things being rocky after independence depending on how your story covers the seperation, but there’s scope for some time to WW1 and a definite alignment to their international allegiances for WW2
The North Atlantic situation would not allow for a neutral Scotland very long
(I’ll mention Orkney & the other islands up there - us Orkney folks have a different mindset, an independent Scotland could have triggered a Norwegian realignment seoerating Orkney to its own independance, and if staying Scottish would have leapt in to support the Norwegians even if Scotland maintained neutrality - the Shetlanders are even more mental than Orcadians so would do the same)
Going back to uniform schemes - starting off plain with a style pretty much the same as the British (units most likely to be the former British Scottish regiments with fresh badges)
The situation could depend on whether it was a clean independence or a demarcation split such as Eire / Northern Ireland - but Scotland does not have the equivalent “English/protestant colony” - if there is a clean independence it would both ease the situation for a WW1 alliance and mean there is no (or minor) ongoing revolutionary action so may not be a need for border forces to be clearly distinct
Into the 90s that could mean an adoption of a Scottish DPM - perhaps the same as the British, perhaps a JimmyCam colour scheme
They may align with the Scandinavians for a pattern, all had some form of disruptive pattern (which could also differentiate from the British if necessary). Some in their own blobs, some in splinter or spots.
Colours tended to aim towards their forest colours, which differ from Scotland’s environment
I would still think of British DPM for the right environment other than a heather colour palette
If allied with England then their expected Cold War field of battle would be Western Europe which keeps
DPM / JimmyCam, but you could come up with a background story to ally with Norway etc and adopt theirs as a Cold War battle ground - but i think that it’s too bright for Scotland
For weapons they would begin with the Lee enfield
But moving on they could easily adopt Norwegian styles - both are hardy environments, Norway went down the HK & FN routes
FN gives a choice between going British with the SLR or to not accept the single fire variant but the full auto FN, and an excuse to bypass the SA80 by rejecting to adopt it with early issues
(Including or excluding the SA80 could tell quite a lot about the attitude on change to independance as to how friendly ties remained)
To build a load out it is clearly a lot easier to adopt a base uniform and create your own badge designs
Mix and match allegiances (I’m inclined on British DPM plus Norwegian accessories)
The SLR edition could still make sense on doctrine of the single shot option due to the common English/Scottish military’s
Have a look at the Irish Defence Force for differences / commonalities with the British for a bit of an independence story, and then look at Norwegian vs British loadouts of the 90s