The bar is pretty low in terms of what is required to obtain your FCA licence. Providing you haven’t got a criminal record for fraud or previously been made bankrupt you will be fine.
Once you have the FCA licence the next step is to sign up with Finance companies that are willing to partner with you. The fact you don’t currently have a showroom will mean that some lenders won’t partner with you however there are still plenty that will. Close Brothers and Motonovo both work with many dealers who are setup similarly to yourself. Which of these companies is best to work with though is very much potluck depending on the Account manager for your area. I would invite them both in and decide for yourself who you prefer.