A button has nothing to do with an immobiliser...that's only central locking. I'm almost certain it'll be immobilised.
Trying other keys is unlikely to work unless you've got a high miler with an almost smooth lock barrel lol. Windows are cheap, I always end up binning them off breakers as no-one wants them, infact I've got a set of 3dr ones in the garage now lol. You can bend the door open a bit if you don't want to break a window...but chances are that'll bend the door pillar, so many 306s have creased door pillars these days lol.
Trying other keys is unlikely to work unless you've got a high miler with an almost smooth lock barrel lol. Windows are cheap, I always end up binning them off breakers as no-one wants them, infact I've got a set of 3dr ones in the garage now lol. You can bend the door open a bit if you don't want to break a window...but chances are that'll bend the door pillar, so many 306s have creased door pillars these days lol.