Split 240 line?

I am in the process of doing a bathroom remodel. The power for the bath was on a lighting circuit (I think 15 amp, its not marked in the panel); this served five lighting fixtures and 1 outlet. My original plan was to leave the lights for the bath on this circuit. I have an unused 240 volt line running to a baseboard heater that is not being used, I was going to remove the 240 breaker, and replace with 2 120 volt breakers and run one to the bathroom, and eventually the other breaker for our living room. A buddy of mine thats been helping with the plumbing says that I don't need to do that, I could just split the 240 line in a junction box, running one to the bath, and the other to a junction box in the crawl space for future use. It made sense, but when I check the cable that is run for the baseboard heater, it looks like 12-2 wire. Forgot to mention that it is a 20 amp circuit. Is it kosher to split a 240 circuit? I want to do this right, and I am thinking that I should change the breaker at the box. If this was a 3 wire cable, could it be done, or maybe I should say should it be done?
Also, should the lighting and outlets be on separate circuits for the bath?

THIS CANNOT BE DONE with that cable. You are correct, you could have split it if it was a "3-wire".
You can convert it to a single 120v circuit, that's it.

If the lighting is mixed with other rooms you cannot have the bath receptacle on with it.
I would leave the lighting as is and use the converted circuit for the bath receptacle alone.

Your baseboard appears to be supplied only 240V, If there is no neutral wire in the cable, you cannot split.