I totally hear you on this one. For what it's worth I got a 2.1 and I was unemployed for a year after graduating so it's not just your degree result. It felt absolutely devastating. Like many people, I didn't do my degree to get a job afterwards, I did it because I wanted to learn, so I too made the mistake of getting little work experience at university because I was too busy studying. Then I beat myself up for that like crazy after I graduated. The reality is that we're graduating into an over-saturated market. When our parents graduated they landed jobs very easily. Sadly for us the majority of 'starter' jobs at the bottom of the rung have at many places been replaced by unpaid work placements and internships, so jobs that used to be paid jobs for graduates are now voluntary, leaving the competition for paid jobs extremely high. I don't think a lot of people realise that until they actually graduate. You're not the only one.
Part of the problem is that the job centre puts pressure on you to prioritise applying for as many jobs as humanly possible - ANY jobs - rather than advising you on applying for the right ones. And I don't mean the ones that are right for you, because in this market you have to take what you can get. I mean the jobs you might actually get. For example, you are unlikely to get hired in an admin or shop role with a degree because they know you aren't going to stay very long. They will choose somebody with fewer qualifications who has a lot of experience because that shows it's something they really want to do. My advice is to re-think your strategy.
I started off applying for office and charity jobs, but quickly realised that the charity sector has no money to hire graduates and offices wanted experienced office workers, not grads. So I had a think about what I REALLY had experience with. I had been a child-minder for a year before I went to university and I had volunteered in a nursery while I was there because I like working with kids, so I started applying for nursery jobs. And although I didn't have a qualification, I found a job fairly quickly after that because there's a big push now to get graduates into classrooms and nursery settings. My second job came from an employment agency that specialised in graduates, and those are also a good bet but you have to be persistent, keep calling and asking if there's anything available because chances are they won't call you necessarily.
Keep your head up. And try to occupy some of your time with volunteering and building your design portfolio. The worst thing about it is the monotony of applying for jobs from home with nothing to give you a change of scenery and a fresh perspective. It might even lead to a job.