Do you think your opponent should be able to block your heal?
Every school has it defense and offense spells to balance with other schools' defense and offense spells. If I am not wrong, blocking and/or limiting the healing abilities is a death school spell. Anyone who knows for sure is most certainly welcome to correct me on that.
If you limit a spell from one school that can be used against you, you will have to expect and allow that school to have one of your school's spells removed to even things out. IMHO not a good idea.
A skilled wizard learns to counter or find ways to minimize the effects of spells used against them defensive or offensive. It is a learning process and skill developing process.
Some options for keeping your health up during battle:
*Don't overload your deck and have enough heal spells so you don't have to wait so long to find a needed heal card. Also, make use of healing treasure cards. Experiment until you find a nice balance of attack, heal, and zero pip cards.
*I like to save one training point to train for the reshuffle card, that way I can worry less about discarding and running out of cards as I now have the ability to reshuffle them back into my deck.
*For my non-Life wizards I like to train life up to sprite. I use sprite in the earlier and middle part of my battles and often that is all I need to keep my health enough to finish a battle without needing any other heal card and it only costs one pip.
*Take advantage of gear that increases the percentage of incoming heals. Usually you can find some athames and rings at the bazaar that have decent incoming heal stats.
I realize there are those that prefer a more aggressive playing style and don’t care to be more cautious regarding keeping their health up early and during a battle and prefer to heal at the last moment. That is fine that is their choice. However if they do choose this style they will have to accept the risk that a much needed heal can be blocked.