Domestic production cannot control the price of a barrel or a cubic meter of gas. Because the UK is integrated into international trading hubs, local supply shifts do little to lower the headline price paid by consumers. When global tensions spike, prices climb everywhere, regardless of how much oil the North Sea yields.
However, the hedge exists in volume rather than price. While you won't see lower bills through increased domestic extraction, you do gain physical security. Local supply reduces the risk of sudden delivery failures caused by pipeline disruptions or maritime blockades. It provides a buffer. If a major exporter shuts down a pipeline overnight, having extra capacity in your own backyard prevents a total supply vacuum.
Think of it as insurance. You pay a premium for it, and it doesn't stop the accident from happening. It simply ensures you have the tools to manage the fallout. Reliance on distant, unstable regimes creates a single point of failure. Domestic production adds a layer of redundancy to the national energy grid. It won't stop price volatility, but it helps prevent physical shortages during a crisis.