Head Gasket or More?

I do believe I blew my head gasket. Check
gauge light came on indicating battery was
dead .  Made it home shit it off then on and
light was off under the hood only thing I
could find was a little coolant around rad
cap. Next day no light so I drove 20 miles or
so light came on.inducating battery was
dead . Went home shut it off waited a hour
or so and started it up no light.drive 5 miles
and it started showing temo going up so I
high trailed it home but it did get hot. So I
saw a ad and was wanting to know if I
bought " Steel Seal For Bliown Head Gasket"
was as good as they say it is,? I cant afford
to the amount of money they want to repair
it.if so do I need a new thermostat? I know I
would probably need new antifreeze.Also it
says it does the heater core but my husband
says I need to unhook it to bypass it.Besides
the antifreeze what esle am I going to have
to get? Thermostat? Flush kit for radiator ?  
Hoes? Clamps,??And any opinions on it??
Appricate any ideas..Thank you