That’s nonsense I’m afraid.
If domestic production is less than 100% of demand, then the pricing of domestically produced gas is always going to be related to global wholesale pricing. This is how commodity markets operate. Why would domestic gas and imported gas - which both end up in the same place - have completely different and unrelated pricing?
You’re imagining a situation where the government controls the supply side and sets the price of domestically-produced gas, which is nonsensical. That situation simply doesn’t exist, and it can’t exist unless the UK produces 100% of its own gas, which did happen when the last Labour government came to power, but certainly didn’t by the time it was voted out.
I also note that you’re (conveniently) ignoring the Energy Profits Levy, which the OBR estimates will raise £40bn over the next few years, through the higher taxation of gas producers.