Not sure what the issue is with careers advice before making your GCSE exam choices at 14. I was in the last couple of years of 'o' level and we had hopeless careers advice but we did have an evening when many large employers (most of whom still ran internal training schemes, long since gone) manned stalls with information about a range of jobs (seem to recall Halifax and BBC). That gave some indication to assist subject choices to continue to 'o' level and consideration of 'A' level choices or what subjects would give you a shot at a decent apprenticeship - the proper 5 year ones!
Personal career advice came down to filling in a questionnaire which was analysed by computer and spat out a handful of suggestions.
Surprisingly I found my result of that a while back and it suggested accountancy or computer programming - I ended up as a mainframe programmer for 20 years and I've been a software tester for 10 years so perhaps it was more accurate than I gave it credit for.
Certainly no job experience opportunities unless you knew someone who could fix it for the summer holiday.