Freelancer is a good tax avoidance scheme
You get to pay no NI, and you can pay yourself a low-tax wage and up to 40k in dividends at 7.5%. And corporation tax is super low for you. That's why we have so many contractors these days. It hasn't added up to much additional productivity because people's skill hasn't gone up; you just pay loads more.
(Having said that, you don't get the crushing pension burden down the road, but then with the removal of defined benefit schemes that's not a problem anyway.)