I got a grant in the very early 1980s. At that point the number of 18yo school leavers in higher education was something like 15%, IIRC. The vast majority of my age group left school at 16, many with no qualifications at all, but some would have been able to study on day release from their jobs, funded by their employers.
For university and polytechnic students, Local Education Authorities had to pay the tuition fees to the institution and a maintenance grant to the student, which was means tested. If the family income was low, the student would get a full grant. My parents' income was not all that high but not low enough for a full grant, so they were expected to make up the difference, which they did, willingly (thanks, Mum and Dad!) as they were so proud to have both their children studying for degrees - not an opportunity that either of them had had. They were both easily bright enough but grant funding was not available when they left school in the late 1940s. My Mum did later get funding to attend teacher training college in the early 1950s. She wouldn't have been able to do that without the grant system as she had to give up her Civil Service job to do it.
My husband went to university as a mature student after working for a few years after A levels. Once you were over 23, the LEA had to fund you without reference to your family income. I suppose if he'd been independently wealthy he might not have qualified for a full maintenance grant, but he wasn't, so he got the full grant in his own right. (His parents would have funded him earlier - it just took him some time to decide he really did want to go to university.)
I feel very lucky to have had a grant. However, the system probably paid for itself as most of us who graduated back then got much better paid jobs later on than we would have done otherwise and we will have paid a lot back in tax and National Insurance.