Petrol bombs and your plans...

[Skvez]

Double glazing is pretty resilient to incoming bottles, so provided your house is brick or breezeblock outer skin an external fire isn't too much of a risk.
If they get a window broken and get a fire inside you're in big trouble. Even if you could put the first fire out (which is unlikely) they can throw more or assault you while you're occupied dealing with the fire. That is the time to bug out the back.