I had one at speed on the A2 many years ago, it's not something to take lightly as i never heard any pop or anything due to traffic noise and concentration but i certainly won't forget the manic rear wobble that followed, a kind of very quick fishtailing feeling.I think the trick is to slow down firmly but gently using the front brake only, and roll off the throttle to let the engine braking help out as well.If you touch the rear brake the rear end will dive downwards, so the outcome then would depend on how deflated the tyre was, but if properly flat could result in the tyre being forced over the rim which could then all get a bit messy. This all applies to being in a straight line and upright of course, if you're on a bend then prepare for take off.
need to look at getting puncture kit, arent some tyres not supposed to be repaired?