You're feeling really rubbish, you know it's likely you've got CV but you're not ill enough to need any medical care.
To have a test you have to leave your home/bed and then you'll get a call from PHE asking you to identify any contacts, who will then have to self isolate for 14 days, even without symptoms. Some of those people will lose money by having to take time off work.
Or you could stay at home and self isolate 7/14 (?) days until you're well, as per the previous guidance and avoid any bad feeling from the people you "stitch up" and cost money.
What is to be gained for the individual in taking the test? I know, greater good etc, but I'm not sure the public is in that kind of mood anymore. How do we make sure the people who need it actually bother having a test so their contacts can be traced?