Hi Albus,
We establish contact with our holy guardian angel within our inner tempel, which is the foundation of our meditation practice. The BoEL teaches, that the holy guardian angel represents ones "higher self". Establishing contact with the holy guardian angel means creating a thought form through which we can consciously communicate with our higher self, for spiritual and ethical guidance. It is a concept, that has been adapted in various magical systems.
To me, the successful completion of it seems like the pinnacle of Western esoteric tradition.
If you have a look at our interactive tree of life, you will notice that the spiritual experience of Malchut is "the vision of the holy guardian angel", or the purpose of one's life. It is the first great achievement on one's spiritual journey from Malchut to Keter, i.e. from Matter to the Source. So, you are right :-)
I would certainly not recomment the Abramelin operation. I have never tried it, but it seems like a practice that, if anything, only suits advanced magicians - for newbies its risks are far too great. Thats only my opinion. The meditation of the Inner Temple is a risk - free method for establishing contact with one's holy guardian angel. Feel free to join our free one-year online course to learn more!
All best,
Benedikt