If a grad scheme requires 280+ points then unfortunately that's just one of the criteria and you're unable to meet it. But the good news is there aren't many grad schemes with this requirement - especially if you don't want to go into accounting/IB/consultancy. There are lots of schemes in general management, IT, science, data, finance, HR, etc with big organisations - NHS, Civil Service, supermarkets, big retail groups, etc., that don't care what you got at A Level.
Some such as the Civil Service don't even care about your degree - you need a 2:2 to access the application system but from then on everything is literally decided on the basis of your performance in the assessments. So with a first there are still lots of options for you - the best thing you can do is get any experience you can and be able to link it really well to the skills required by the scheme.