Some toilet repairs can easily be handled by yourself. The most common repairs on a toilet are usually the ballcock(valve) or the flapper. The only tools needed to do those repairs would be a razor knife and a channel lock.
If the tank or bowl needs to be repaired or replaced most of the time the bolts need to be cut off and you would need a professional to handle those repairs for you.
Remember most plumbing fixtures are made out of china and can crack easily. Be careful when working around plumbing fixtures. If it cracks or shatters you will probably need to make a trip to the emergency room.