If you can find them. More innocent victims will inevitably get caught in the attempted attacks on the IS words removed.
If they would all line up in 19th century marching and fighting formation out in a field somewhere then we could napalm them.
Unfortunately, dropping a bomb on a village they've seized causes a 6 year old boy to see his mum or his sister killed....and off we go again, with revenge for the revenge on the revenge (see Palestine).
As for troops n boots on the ground, see Iraq and Afghanistan.
It's a bit of a sticky situation.
Back in the day when we had an Empire the Brits got really good at what were called punitive expeditions. We'd send in 5-10,000 troops to find, fix and destroy as many of the enemy as possible and then leave again. No occupation or nation building that keeps you there for years, just a few months roaming around and doing the necessary.
Translated to the modern era I'd suggest an up scaled version of the Long Range Desert Group which operated in North Africa during WW2. Lots of mobile columns operating in the huge empty spaces of Eastern Syria, ripping up their lines of communication and supply, locating any concentrations of enemy forces and destroying them from the ground and air.
It's the kind of job that UK, US and French conventional forces are very good at, which if coordinated with Kurdish forces would really change the balance of power on the ground.
Simply bombing IS will never make a strategic difference and I don't see how the current situation can be tolerated any more. Sure it would probably lead to a few more attempted terror plots in UK but they are trying to do that already, and frankly anyone motivated to launch domestic attacks for giving IS a shoeing aren't people we should want breathing anyway.
No nation building?
Didn´t you draw many of the borders that still exist?
Anyway, it is clear that the west want to get rid of Assad and that he has allies of some power.
He is winning alot of lost ground back from Isis (useful idiots turning out useless) and have no reason to permit western troops in Syria.
Finally...We are broke.