I have previously contacted the RHLI, who informed me they had just done a large recruitment and would not be taking applications in the near future. Truth be told though, now that I've gone through the process of applying to the Argylls, meeting some of their officers, seeing their mess, researching their history, I'm still really determined to join that regiment especially because of it's continued use of highland dress. That may seem like a silly reason to continue to apply to one group over another, but the connection to my own history and heritage is a large motivating factor for me in this whole endeavor.
As for other trades besides infantry, I have spent a great amount of time perusing this forum as well as various recruiting websites and studying the available occupations. There are others that interest me in varying degrees but it is infantry that I wish to pursue at this time.
So I'll probably be contacting the Argylls alone for a while, pursuing my desire to be a part of that regiment is foremost at this point. If in the next few attempts that does not work out then I will begin to consider other occupations including NCM with the Argylls, or positions in the other fine units in Hamilton you have described.