From that page you'll need the link about Self Assessment: https://www.gov.uk/log-in-file-self-assessment-tax-return
If I register, am I going to have to file this shit every year?
Basically yes, until you convince them that you no longer need to file a tax return. But, if you're half way organised and have simple affairs, it takes half an hour once a year.
@hippy started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
From that page you'll need the link about Self Assessment: https://www.gov.uk/log-in-file-self-assessment-tax-return