I’ve levelled a warrior in all different specs before. You don’t need to level up as prot to do tanking, in fact, arms is probably better. You get talents like parry and anger management anyway, which help with tanking, and you are much more viable when soloing and can dps some dungeons if you get bored of tanking. Arms is the spec for you.
Asking your group for money to repair your armour won’t go down well. Part and parcel of being a tank is that you are taking the responsibility of taking the damage and any repercussions of that. Be a leader and repair your own armour.