I'm due to go on a job interview for a team leader (C#, Mobile applications) position in a few days
I learned pretty much everything I know by myself (at work, at home) - I do hold a B.Sc. in CS though.
So the thing is - I think I'm terrible in job interviews - they always get to ask me questions that I don't really know (like specific programming questions, sometimes even questions considered basic) the answers to.
I never went through a complete programming course in C#, so there are alot of subjects I'm probably not even familiar with, which (I assume) I will be asked on during the job interview.
I never considered myself as an expert in a specific programming language - for instance, in my current position (I've been working on the same company for almost 6 years), I mainly had projects in Delphi, C# and HTML5+JS and along that, I had to code a few things with PHP, PL/SQL, and Java.
Some of the projects I worked on were designed&mostly implemented by myself, and are now being sold to our clients (2 of them are large scale, in terms of endpoints), and I think they're a great success, management does too.
Is not having a specific programming language expertise a drawback? How do I sell myself better? How do I avoid presenting myself as a total newbie when sometimes 'not knowing' the answers to rather basic questions?
EDIT: Thank you all for your answers - they did help me alot during this interview as I had more confidence comparing to previous job interviews I had. Too bad the employer itself wasn't ready - the guy who was supposed to interview/test me wasn't even prepared (he didn't even hold a copy of my C.V.), I felt like they're not taking this too seriously, eventually I was told to go home and call them back to re-schedule for another day, so I told them to call me back when they're actually ready.
There're no "wrong" answers here - so +1 to everyone