You've taken the first step to getting your life back. It IS a huge step, but as you have mentioned, when the IP explains what's involved it all seems far too straightforward. I kept waiting for something to jump up out of the blue and make a hash of things, but it didn't. It IS that easy.
With regards to it becoming protected - there is a smidgen of a chance that it won't, but I doubt that. The creditors will realise that at least with the TD they are going to get something back. If it fails to go protected they will get nothing.
In five weeks you will be able to let out a sigh of relief, but trust me, you have nothing to fret about.
Once again - well done. In 36 payments time you can start over again and be all the wiser for this hiccup...