It's unlikely your acetylene torch will work with propane. Oddly enough different gases have different chemical properties. There are seals in the torches that propane can dissolve... acetylene seals are made to resist acetone, so they might not always be compatible with propane. Some torches are made for different gases, as well the regulators, and they will usually have it clearly marked, esp. on regulators "for all fuel gases".

I would really urge you to do some more research at an actual welding supply shop instead of the internet. Surely professionals (of any trade) still use oxy-acetylene rigs in the UK, find out where they get their stuff.

Personally I try to avoid jerry-rigging medical equipment when the right tools are commonly available. I didn't notice anything on the BOC site about acetylene being a restricted substance but maybe it is... IDK. Surely if you have acetylene regulators, hoses and torches it makes sense to just go with acetylene as a fuel?