Is it worth tuning an engine to gain less than 10hp. I have a 1.8 insignia and its performance is terrible. Have seen some cheap-ish maps out there but the gains are not superb!

for racing yes...for the road, no...too much work for 10hp+...

Yeah... only for racing...

It's definitely not worth paying £200+ for a tune that will give you +10bhp, if you've got time and want to mess around why not? Just don't expect to be able to feel any gains, you'd only be able to tell with a Dyno.