The question is perhaps a bit out of date.
'We' are already bombing Isis in the form of the RAF bombing them in Iraq.
'We' are already bombing them in Syria in the form the of the French Air Force conducting missions in Syria.
Hopefully it hasn't passed un noticed, but young kids from the UK have already been leaving in large numbers for Syria. They have come from all over Europe to join ISIS and fight 'us' in the form of western people in Europe and 'bad muslims' in the Middle East.
If someone is naive enough to believe that Isis wouldn't target the mainland uk (again) as the RAF aren't flying over Syria then I may have a bridge in London for sale that's going cheap
