There’s nothing legal about it, you are contriving gas safety regulations so it’s absolutely not legal, if it was a cooker that would be fine but not a hob
If you had one cooker and the bayonet fitting was in and brought in another cooker which already had a hose fitted, all you had to do was swap them that’s fine but it’s when you have to install stuff that you need someone.
There’s nothing legal about it, you are contriving gas safety regulations so it’s absolutely not legal, if it was a cooker that would be fine but not a hob