Look after plants, in what sense? As in, working at a local plant nursery? For the local authority? Becoming a farmer/agricultualist? Looking after gardens in general?
I've always loved messing around in the garden, learned it as an infant, have built gardens (even if in gro-bags) wherever I've lived. I now work as a self-employed gardener. No formal qualifications; after being made redundant and being on the dole for too long, was just invited to help my first two clients and it took off from there. Many of my clients (elderly with much loved gardens that they can't tend any more) comment that their gardens have never looked so good, which coming from these particular clients, is really quite an accolade. What I don't know I can find out about on the internet.
On the other hand, you would be utterly astonished at how little some people know about the plants in their gardens. Even watering their plants seems like high technology!
I had a highly skilled professional job when I was laid off. With less than half that income now, I can honestly say I love being in the gardens and it brings a whole new set of "rewards" and satisfactions. Unlikely to become a millionaire, but there's more than enough to pay all the bills.
Be prepared for too much work in the summer, and only just enough during two or three months in the winter. Have fun and enjoy life.