If Malaysia can't obtain 30% of its fuel because of the Hormuz closure, they don't just reduce their consumption of fuel by 30%, but make up for most of the deficit by buying it for a higher price somewhere else. But the fuel they buy to make up for the deficit simply means there's less fuel for other folks buying in that market to purchase, which drives up prices. This process repeats until prices stabilize worldwide, which ultimately results in higher prices for fuel in the UK.