I\'m the only developer in my (very small) company and I\'m about to start on a medium sized ASP.NET web application for said company.
I\'m trying to figure out if
Note that TDD is not about testing; it is a development process. The testing is not done to replace the testing function - it is what defines the dev process.
It sounds like you are talking about unit testing and other automated testing. Testing is good. Automated testing is good. Don't be afraid to make mistakes. If you think about your code and how to automate testing as much as possible then you are in a good position - however there is a cutoff of diminishing returns. 100% automated testing is probably not something that is cost-effective - especially for an organization that you describe.
If you are really talking about TDD (What the experts would call TDD), that can also be good. There are many development processes. It is good to remember that development processes are frameworks and guides - not a religion to be followed like a quest. No process is one-size fits all. Do what makes sense for you and improve as you go. Having just one person in a dev organization makes changing process fairly painless. Address your high-risk issues first and put some lightweight process in place for those before going after low-value issues.