Let’s be sensible, here. I know nowt about the rules for acetylene, but….
Location may make a difference to the rules/laws. You have not provided that information.
As above, there may be a difference between a discrete workshop building and one which is part of your habited house. Again, you have not provided details.
Most certainly, butane bottles within the house, in the UK is permitted. Propane is not (because of the higher pressures involved). All calor-fuelled cookers, etc must have the bottles sited outside.
Non-flam gases are permissible – lots of oxygen cylinders are used for people with breathing difficulties. Soda-stream bottles have been in existence for decades, some fire extinguishers contain CO2, some even run bars in their homes!
However, in any case, your house and contents insurance may be negated (if you think you are insured) unless the company is aware and the policy adjusted to include the risk.