Whilst it's likely that we will lose oil/gas delivery over time from the North Sea, with the 9 to 25 year window* before a new license will reach the produce stage anything which is granted now isn't going to impact us for probably a decade, and maybe more.
As such, if we do consider our emissions from the production of something they aren't going to be altered in the short term. However if we don't then we shouldn't be producing any oil or gas as then those production emissions are counted by other people and not us!
Of course taken to its extreme there's no emissions from building my car as that's production emissions, so if I buy an electric car (where the emissions from the building of the car are significant but over the entire lifetime generally end up lower than an ICE) and it only ever powered by solar from my house, then this is as good for the planet as walking everywhere - right?
*Timeline taken from this UK Aid document on likely timelines which then core two sources for its information:
I would prefer the situation you have outlined to the UK sending £10s of billions a year overseas when the UK has oil and gas that could be extracted instead. I don't agree with the "Net Zero" appproach because it results in economically disastrous and non environmentally beneficial outcomes like importing oil and gas rather than using our own reserves. My view is that we need a policy that is specifically about decarbonisation and technology driven, not about "carbon budgets". We should decarbonise as fast as is economically and politically viable. In the mean time we should max out the North Sea reserves. A "low pollution by 2050" policy would be an easier sell in the red wall etc than "net zero".
It will be interesting to find out what the minimum 2030 range requirement for hybrids will be. If its enough for day to day journeys and commutes e.g. 100 miles when brand new, it should be practical and affordable to switch. I am more concerned about 2035 EV only deadline which is a bet on better battery technology. If 2030 hybrids have enough range for day to day journeys they will bring forward most of the benefits of switch to EVs. The average emmisions of a hybrid car that is charged at home with a 100 mile battery range will be a fraction of an ICE. Most people rarely drive that far.