Oxygen bleach should be fine on nappies. You can put a scoop in the washing machine or soak them in it for a few hours. Neither soaking or (any kind of bleach) is recommended by most manufacturers but an occasional use won't do much damage, particularly if you stick to the least damaging kind i.e. oxy/eco bleach instead of chlorine. Quite a few manufacturers do actually say oxy is fine. I used to use Dri-Pak's laundry bleach but they stopped making it... it's the same stuff as Violet's but was LOT cheaper. I used it to soak various things including nappies occasionally to treat for stains and it never seemed to do any damage. You could at least soak fitteds and inserts in it (I'd be happy to do outers too, personally), then wash everything in GSE at 60 degrees.
I wouldn't bother switching to sposies while treating but if you wanted time to treat the nappies or extra peace of mind, you could probably buy a pack of 12 prefolds for about a tenner preloved and use them until you're all clear. As well as the really interesting research the US nappy peeps are doing, you can pretty much do anything to prefolds so if you wanted to wash at 70 or even 90 degrees while treating, that would be okay as long as you left out the wraps!
