Autonomy is a co-op principle, but that doesn’t mean you must (or can!) do things on your own. You’ll likely need to seek expertise in the broader community.
The help you need will depend on what you plan to do. Acquiring an existing building is less complicated than developing a new building on an empty site, but lawyers are needed for both. Financial modelling is critical to get a sense of whether your project has a chance to succeed. It’s also necessary if you’re hoping to borrow money or apply for grants from potential funders.
* Would also include possible accountants, marketing consultants, etc.