Maybe see if his student account offers one initially? The problem with applying for any other, is that he may not meet income criteria.
My DS got offered one when he went to uni, with his student HSBC account, £500 limit. He is v financially astute and careful, so used it only for train fares and the odd small purchase, primarily to help build his credit rating. (He has a large inheritance as a deposit so the chances are that he will look to buy a house fairly soon after starting first job, so a decent credit rating will be useful)
He has just finished a year in industry job and discussed wanting a higher credit limit for when he travels after finishing uni next year - he couldn’t increase his HSBC limit, so applied for a second card whilst he had a good income to offer (and has got one with no foreign exchange fees.)
DD is also going off travelling as well after a year working in retail. Again, her salary isn’t great, but she did get one, albeit only £1k limit, but enough for emergencies if she were to lose her debit card abroad (although she has since got a cash card for free when booking her flights).
There is a card checker on one of the money sites, it allows you to see what you are eligible for, which is what we did with DD.