"Jamie Oliver is a home cook..."
Jamie Oliver worked as a sous chef at the River Cafe, an Italian restaurant in London. When Jamie was working there it was awarded a Michelin star (which it still has to this day).
So, I think it's likely that he learnt how to be a bit more than a "home cook".
In contrast to that though, he did say that one of his inspirations was somebody without any formal training at all - Keith Floyd.
You may remember him from his various cooking shows in the 1980s and 1990s.
Some of his shows are still on BBC iplayer, such as his 1987 series 'Floyd on France'
https://www.bbc.co.uk/iplayer/episode/b03j5hgr/floyd-on-france-1-provence