#1
I know it's likely not gonna sound the same if I repair it, but the break didn't get to the fret board. So is it worth repairing, what should I use to glue it back on,? should I get someone else (guitar shop) to do it,? will it just break again due to string tension?

It's neck through, I assume it'd be easier if it were bolt on.

If it's unrepairable it's got a lot of upgraded and good stock hardware, I'll probably buy a cheapish guitar and just use the parts off my broken guitar.

So what should I do?
#2
The more surface wood is exposed the better a joint will be so its entirely possible to glue it back on depending on how its broken. If you can, upload some pics and some of the more experienced luthiers on here will be able to tell you if its likely to survive. Gibson headstocks break and get glued all the time.