I think that the OP may have put the cart before the horse here. It is a bit like all the snowflakes who go to UNI paying large tuition fees and end up with a large student load and a job filling shel in Tesco’s. You may find a DNO who will take you in as a trainee engineer and after you have done their training the money is very good and you can keep your hands clean.Where in UK do you live ? Most Utility companies have well paid apprenticeships if you can take a bit of financial hit for a year or two.
For example WPD pay design trainees (need HNC electrical engineering) £28K. Should add they pretty much don't need to know anything about BS 7671 so you're halfway there already!
back in the sixties I started with the LEB ( London Electricity Board ) as a trainee engineer. I had one A level therefore no good for UNI but I did ONC year 2 and then HNC in Electrical and Electronic Engineering. I learnt a lot on the job and got some really good hands on experience. After four and a quarter years I passed out and was offered a job as a heavy current distribution engineer with the LEB.
i can honestly say that from that day on the only part of my HNC that I used at work was Ohms Law. The rest was H&S or based on my previous on the job training. It was a good job, and though the hours were long and lots of emergency call outs, I throughly enjoyed it and it gave myself and my family a good standard of living. I got out soon after Margaret Thatcher sold off the Nationalised ESI.
so I suggest that the OP gives one of the DNOs a try.