You don't need to worry using directly the SOX.
I meant using directly the SOX lamp with the full circuit to tset the ignitor, there is no danger for the lamp regardless on how possibly the ignitor may misbehave (when still not fixed due to any reason).
Either the ignitor is working, then the lamp will start normally right away.
Or the mains voltage happens to be enough to ignite and support the discharge (however this is very unlikely scenario), so it will start seemingly normally as well, so no risk for the tube.
Or the ignitor won't work and the mains is (as expected) not enough, so the lamp stays essentially off.
No need to mess up with some fluorescent lamp in order to test the ignitor, you may just get false results (even the perfectly working SOX ignitor may not be enough to support the cold electrode operation of many fluorescent tubes, which may mislead you to thinking the ignitor is not yet working or so).