Contrary to popular belief, not everything can be patented. Inventions must normally relate to something technical such as a product, a machine or a process rather than to something like a marketing idea or a method of doing business.
You do not need to have made a prototype but you should have a good idea of how to put your invention into practice. What you must also do is file a patent application as soon as possible but certainly before you make your idea public in any way at all, as even telling someone about it can jeopardise your ownership. An initial search can be done, but it is the patent application which will establish your 'priority' date as to ownership.
If you also want protection in other countries as well, then you have twelve months to file applications covering these territories, and will then have the benefit of protection from that same initial date.
Patents can last for up to twenty years and can be a crucial element to a business success. You should consult a patent attorney at the earliest opportunity.