Thanks Phatbeetle! Got a scan today and there's no DVT, so that's really nice. The doctor said they aren't exactly sure if it actually is cellulitis but whatever it is would get the same antibiotics so whatever.
It was kind of funny because I had a really nice junior doctor who really wanted to dot every i and cross every t. She was talking about me coming back next week for a follow up visit. I was willing to skip it and only come back if things got worse. Then the supervisor cam in and was like "No, he's finished, let him follow up with his GP, we are done". Long live the NHS!