TCS won't always save you: It can cut the power so abruptly it can pitch the car the other way, especially if you've already started trying to correct it. Good TCS is excellent, bad TCS an absolute liability. In the Zed it saved me once vs the dozens of other times I needed to make a quick getaway and it left me stranded...
But yeah, for the most part it's a good thing. Fair play for trying to learn the car with it off too: It's almost better to do if this time of year as stuff happens at slower speeds, rather than in the summer when you need far more gas to get things to move.
In terms of driver training, I believe that Walshy now does his Carlimits.com days up north too. I've been out with both Walshy and his mate that he ropes in, both excellent teachers as well as really good guys. I wouldn't look anywhere else tbh, and even if you have to travel to Essex it's worth every penny.