Welcome, George - it sounds like you are doing pretty well to me!
Definitely use your Welsh as soon as you’re ready to! And I mean as soon as you are ready, not when your Welsh is ready. It sounds like you’re ready now, so go for it!
Listening to the radio is a great idea, and don;t worry about the accents - as you get more experienced with your learning, you will start to be able to differentiate between people you understand a bit of, and people who are impossible to understand. And you will get a broad range of listening experience that will only help you to improve and naturalise your own language as you develop.
I’m interesting that you are finding it “harder than suggested”. There are two main things that might make our course difficult, I think. One is working memory difficulties - there’s nothing much you can do about that except to keep pluggina way, and letting the “mental muscle” build. You will find that you get better and better at the short term remembering needed for translation and recall of words in the excercises.
The second thing is an over expectation of the instant results. That we can deal with quite easily, depending on your willingness to change your attitude to mistakes. We get trained in school to avoid mistakes at any cost, and to learn “the unit” before moving onto the next one. That is not how SSiW works.
The best way to work through the challenges is to just fly through them “bull at a gate” style, saying the first thing that comes into your head each time we give you the opportunity to speak. It doesn’t matter if these are right or wrong, as the Welsh that follows twice will “correct” your subconscious. What is important is that you get used to coming out with something fairly quickly, that is relevant to the English sentence that you have heard.
Don’t try for perfection, ever, and don’t think that you have to go over challenges again and again to “master” them, just go with the flow, and trust the system.
In other words, if you are finding it fiddicult to get the challenges “right”, then don’t see that as a difficulty, but jsut as part of the process!
All the best, and make sure you enjoy the trip!
Iestyn