While it sounds really fun, I think there should have more flavor. Instead of using the generic name "magician", it should be a "Hedge Witch". You know, since she has no particular training? However, what the Hedge Witch lacks in education she makes up for with adaptability and raw power. In fact, Hedge Witches would sometimes have trouble controlling their power, so they might occasionally suffer some adverse effects when channeling, hence why they can't be properly educated in a school.
Also, because of their versatility (as well as their lack of education) perhaps the Hedge Witch should have higher channeling but lower spellbook points? I'm thinking around 100 or so spellbook points and 12 channeling. I think the Hedge Witch's versatility should come more from her spellbook design then from actual play. If you want a mage with tons of versatility in play but less in designing their book, I think a good idea would be a pictomage, that can make their art real. The pictomage would be trained in Water, their creatures would be shapeshifting ink blobs, and they would have enchantments and incantations that could copy or steal spells from the opponent.
What do you think?