I can't advise on the TES seminars as I've never been on one but I have been for a personal appointment with Theo. I think they have 15 or so people at the seminars so, while I'm sure they would be good for general advice, in your case as it sounds like you need personal help with your interview technique you might be better off going for the one-to-one appointment. If you can afford to go I would definitely and completely recommend it. Theo did a mock interview with me and gave feedback straight away on everything from my answers to my shoes! You can email Theo's assistant Julia for details of cost and dates at: email@example.com I don't believe there are any books specificallly on interviews for teaching (unless Theo is going to write one!) but you could look at Great Answers to Tough Interviw Questions which is the bestselling general interview guide (I used to work ina bookshop) and read Theo's interviw clickables if you haven't already. Good luck!