Whatever you may think of him:
Captain? = Yes
Wiki tells me that he was supposedly the first British officer to enter the Kosovo capital = well he was in Kosovo but not sure about first in.
that he used keep his guitar strapped to the outside of his tank and would perform for the locals = Don't know
and he was champion skier of the entire Royal Armoured Corps = Yes, skiied for the Army
and he stood guard over the Queen Mother's coffin = Yes