A few options here, really.
Option 1) Level enchanting and smithing together by smthing iron daggers and enchanting them. Preferably with Banish or Absorb Health, as these will jump the value of each dagger to the thousands and this way you can make money. Protip: If you get speechcraft to 50, you can sell anything to any merchant, so this way you could do things like train your destruction magic up at the college or buy new spells, then sell the iron daggers to the merchant with his/her newfound money you just gave them.
Once you have these leveled sufficiently, you can smith yourself some nice glass/ebony/daedric/dragon armor, depending on what you want, and enchant these with all the perks you would've had on your mage robes. Don't forget to enchant some smithing gear, then wear your gear while you enhance your new armor to Legendary! Protip2: Get the Steed Stone while you're training your Heavy/Light armor skill, that way your new armor weighs nothing while it's on you.
Option 2: Make sure you are not wearing ANY light or heavy armor. Get the Stone/Ebonyflesh spell. Get the alteration perk that increases the effectiveness of these spells, make sure you constantly have these on. Even better, get Alteration Magic to 100 and then get the Dragonhide spell to reduce 80% physical damage. Protip3: If you'd rather grind your skills as opposed to allowing them to scale with you (I personally don't recommend it, makes the game less fun) then if you use the alteration spell Telekinesis you will level Alteration scary quickly. If you have the ability, enchanting armor to get a 100% reduction in magicka cost for Alteration can probably go from level 1 alteration magic to 100 in an hour by this method. Again, I don't recommend it, but the idea's there.
Option 3: Increase your health instead of magicka via enchantments or strictly leveling up. The only reason I'm honestly posting these is because I said a few options and then only thought of two.
There're likely other ways, but I can't think of them. Have fun! Pure mage rocks!