I have never done the TSS course - looks good, but I have held off doing it because it is mixed levels and mixed ages - so I have always felt (as a fairly experienced and confident sculler - but wanting to get better) that I may be waiting for people who are working out how to get in. (If I am wrong someone let me know as I row opposite the club!)
Tideway is also a challenging environment to learn technique - survival yes :)
I would recommend any of the courses by Allan Whitwell - he does week long ones in france (which I want to do) and a weekend at Weybridge http://www.weybridgerowing.org.uk/
(which I have done). I think he also does Perterborough.
I would also LOVE to go to Craftsbury Sculling Centre - one to save up for.
Nothing like being looked at by a coach, but I would also look at the DVDs that are around by the UK coach - don't have them to hand, but will put them up later.