Are time serts fairly easy too use, and would it be safe to use in the cylinder head?

 

What part of the cylinder head are you going to use it on? A heli-coil is another option.

 

i went and got a heli coil kit, but i didnt use it yet, because i dont have a tap wrench...its the bolt holes where the valve cover bolts too

 

If the VC bolts thread into a raised boss, you have to check whether there's enough metal around the hole, after you enlarge the hole for the HeliCoil. If that's OK, then go for it. Those are not high-stress bolts so a HeliCoil should be OK.

I think but not real sure; that a HeliCoil needs less enlargement of the hole vs. a TimeSert.