FYI - reserving a name in CA only holds that name for 60 days and you can't use "Inc", "Corp" or "LLC" unless you register. There are different forms and fees for C-Corps, S-Corps, LLCs and DBAs. Depending on the nature of your company (e.g. how many shareholders, partners, employees, etc) you may want to consider consulting an attorney to help you select the type of entity you want to set up and with filing the proper documents. You can use online filing services such as LegalZoom, but they tend to provide only bare-bones vanilla templates.

BTW - good luck with your new company.

So to make certain I am getting all of this correctly, I could secure the name "Clown Baby Software" for a studio prior to registering the business? Wouldn't I need to prove I have a reason for trademarking the name?

In the UK you can register a trademark if you use it to trade or intend to use it to trade. I don't know if there is some requirement to prove that you intend to trade - I assume that there is a limited time from registration of the mark to commencing its use in trade.