Do people fix cx tubulars after a flat just intrested.

Yes.

http://www.totalcycling.com/a-z/puncture_repair/prv_pitstop.html

or failing that

http://sheldonbrown.com/brandt/tubular-repair.html

or even

http://www.tubular-repairs.com/

depending on how much your tubs cost in the first place I guess!

I usually just use some Stan’s or similar sealant. If that doesn’t work then that’s it.