Fluency is a weird concept, because I think fluency is dependable on what you need to do with the language.
There’s a video on YouTube which I used to give to people who’d ask about fluency and for the life of me I can’t quite find it now, but the guy does a couple of things.
He reads the first page of a very, very, very technical book on something to do with how car engines run. The idea being that even though most people who watch it are fluent English speakers, he goes on to say that unless you have a very good knowledge of auto mechanics - the vast majority of it will not make sense to most fluent speakers.
He then gives the following example.
Take a person who has studied for a PHD in automechanics in a foreign language. They know the language well enough to detail extremely technical documents - but say for instance this guy doesn’t know the word in his target language for “Supermarket”, “Ice cube” or say… “Pie” and outside of his course he rarely speaks to native speakers.
Take another person who has just been travelling through a country for a few months, picking up colloquial language along the way, surviving by learning the language as they go. This person cannot write technical documents, but they know the words for “Supermarket”, “Ice cube” and “pie” because they come across them every day when they are out mixing with the locals.
Who is more fluent?
A lot of what we consider fluency really equates to “How much of my life can I live in my new language?”
I consider myself “almost” fluent (if fluent is such a thing). What I mean by this is that I have a great deal of friends now that I only speak to in my new language, I have a whole social circle to whom to speak to in English would feel incredibly weird. I can go on nights out and spend whole days with people without muttering a word of English. I’ve been able to give presentations in work in Welsh, because I’m talking about a subject that I am familiar with.
Could I go to a Welsh mechanic and explain to him that I think my alternator is not kicking out the right voltage because I find my car stalling sometimes half way through a journey? No way!!!
I blabber on (you’ll get used to that!)
Bottom Line: I’ve done all of the lessons currently available to me as a South learner and I can get by in every day life in Welsh without a hitch or problem. I’ve worked hard at it, but my achievements are not “special” shall we say?
If you do the course and live a life similar to mine, then you should be able to go whole weeks at a time without using English (ironically my biggest use of English at the moment is on this very forum!!) but if you are looking to have enough Welsh where you can use it in a job as a nurse or an insurance salesman - you may need some extra work on the side