Even back in 1982 the British government's policy on the Falkands was that they had a right to self determination and as they wished to remain British then they would be liberated from the Argentine invasion. To reinforce that point I heard a transcript yesterday or Monday on the One Show of Thatcher saying exactly that. Perhaps OP, you could see it on IPlayer?
Our policy has been since 1945 the same for any overseas territory. There has been wrangling on definitions of protectorates etc on this thread. The key words are overseas territories. As long as the people of those territories wish to remain part of the UK and her overseas territories then they will and will always be protected.
We also go to some lengths to protect British citizens living overseas in countries where it may have become dangerous to live and we always offer to get them out and back to the UK. IMO we should always have enough military forces available to carry out that role.
Under NATO and EU treaties and agreements we protect and defend (and yes sometimes per-emptively). Without our involvement we would be unprotected. We are reducing our military yes, but this is with a concerted effort to share resources with other NATO nations.
I find it so sad when I read on here people saying there are 'some good people in the military' as if these are in the minority. I also find it sad when people appear to lack any sense of respect of our military and are scornful. I also find it sad when people find a military presence scary and unsettling when the military are there to protect our interests. The vast majority are fantastic. There are always a few bad eggs, but in no way should people let that colour their overall opinion as that's monstrously unfair.
I personally would love to go to Zimbabwe to stop the stupidity. Funny how all those white people being persecuted are not being protected by us other than our offer to let them refuge in the UK.
I suppose it also worth remembering we probably are in many areas but it's either not widely publicised or not releasable to the public. 2 areas that are publicised but seem to be often forgotten is the Royal Navy's presence in the Carribean and also anti-piracy in the Horn of Africa. Both enabling capabilities which should not be under-estimated.