I think that whatever Sunak has said, it will not help his intentions succeed. Reforming the education system can be hugely helpful, but this new 'british standard' system is just a way for Sunak to feel he has caught up with the education systems around the world. Forcing people to take english and maths for higher study, whether they like it or not will make students' lives very difficult - especially if they lost their will to do it at gcse.
It also completely takes away the 'choice' students have after gcse to go for either a levels, t levels or apprenticeships to name a few, and merging a levels and t levels will take away what students really want from their education. Some people are more academically inclined and some people prefer practical-based learning.
Secondly, every student has their own will to do what they want to do in life. For some people who want to study at university, having to do english + maths and 3 other subjects can take away from what they want to study in the future. For some people who want to go straight into employment, they will be left with fewer options that gives them that experience that employers are looking for.
Also, rather than trying to muddle up the education system that has already been formed, the government should focus on improving the teachers' workload/salaries, improving quality of lessons for students and helping students with special needs/learning disabilities succeed rather than struggle in their learning.
On top of that, there are a lot of things that need to be done outside of the education system, like manage the economic state of the country and help people who are financially struggling because of it - like the nhs may not have enough resources or staff and similarly there are train strikes and teacher strikes going on too.
If Sunak's attention was focused on what the country really needs to improve, then it would be a lot better situation.