I like the idea of using destruction for a cloak spell but like you said it's kinda clunky to switch in and out of wielding my greatsword. I also wanted conjuration but again with the switching.
Honestly, if you want a smooth "Introduction to two-handed" playthrough, just stick to the standard Smithing-Enchanting to get good armor and resistance gears, with a good weapons to go along with. Might want to go with heavy armor if you play two-handed the first time, because that moment of inertia after you attack is when you are most vulnerable because you can't move. I still prefer Light armor though, less perks, same protection in the long run, and both trees meet at Dragonbone weapons; which are the best.
Go Archery if you like, take out archers and mages, soften up targets and finish them off at close range.
To supplement magic into two handed build is more like the battlemage. I usually cast Alteration and summon Atronachs BEFORE combat so I can focus on picking a target and rush him ASAP while my Atronachs aggro the range attackers. try to finish combat as quick as possible so you don't have to switch in and out healing spells.