Depends on your preference. Some people will say you don't need any formal education and can learn by starting small.
If your serious about it then why not do both. A formal qualification and start with a small development at the same time.
I wouldn't necessarily do a formal education in building / construction. That is only one part of development you need to understand but you don't need to be a specialist in it. You will hire a builder.
A developer acts more as a project manager and needs to know a bit of each field: building/construction,town planning, architecture, finance, negotiation, etc..
Andrew