There are several distance learning postgraduate courses in librarianship now if that appeals, including Aberystwyth, there is also a new course starting this year at Manchester which combines archives and library skills (they, ahem, borrowed from UCL judging by the course content out so far). Even working in libraries is going to involve dealing with people though, especially in entry level jobs. The days of being safely tucked up in a cosy nook in a library basement are long gone. If he wants to go into that field he really needs to get some experience, even volunteer experience to start with if he can.
If libraries appeal, what about looking for cataloguing or metadata type jobs? NBS used to advertise quite regularly, I think they have just advertised. At the moment there are some library apprentice type jobs, including in the NHS, where you get your course paid for as you work. Or something like trainee coder in the NHS (though I don't see those as often) or records management, and another field that appears to be growing is cyber security. All require attention to detail and diligence and have clear structures.
He's got at least 45 years of work ahead of him at current estimates, and it's likely whatever he decides to go into he'll have to career change at least once in that time. Depending on where you are in the north there are some good civil service roles including HMRC though they are very pedantic about how you complete their applications - lots of good advice on here, YouTube and various other sites.
Has he talked to his uni careers service? When I was in my 20s and struggling to get interviews they gave me some invaluable advice on sorting out my CV. Best of luck, it's one of the toughest points of your working life, I think.