Caveat: I've never been to the UK, nor have I ever spoken Welsh with another speaker. My Welsh speaking/writing has entirely been confined to SSiW lessons, Duolingo, and this forum. So feel free to dismiss anything I say here because I'm probably not qualified to have an opinion.
However, I want to expand on something that Kate touched on briefly:
This "all or nothing" is a really important point for beginners such as me, whose standard of Welsh so far is even less than "getting by".
When you all talk about learners speaking Welsh with native speakers, what kind of expectation do you have? (By "you", I mean both you within SSiW and you as members of the wider Welsh-speaking community.) Do you feel that we should speak entirely in Welsh, however poor our grammar or however wrong our mutations or whatever, and if we just can't find the Welsh words we need, we should give up the attempt and say that whole sentence in English instead?
The reason I ask is that I have an uncomfortable feeling that I shouldn't find a conversational partner and try out my Welsh until I know far more Welsh than I do now. I don't want to make stilted conversation about old dogs and young cats and buying beer and playing rugby. That's fine for lessons, but I want to talk about the real things going on in my life, and I'd probably feel much braver and give it a go in Welsh if I knew that people wouldn't mind my throwing in English words or phrases whenever I don't know the Welsh for what I want to say.
For example, suppose I'd made an appointment with the vet for tomorrow. Would a conversational partner mind if I said, "Bydda i'n cymryd fy gath i'r vet prynhawn fory"? I don't know the Welsh for "vet". I don't know whether the rest of my sentence is even grammatical. It's only my best attempt, and is probably full of errors anyway, even without the word "vet".
But I might be willing to give it a try, basically saying whatever I'd otherwise be saying in English, whatever is relevant to my real-life situation, but replacing the English with as much Welsh vocabulary and structure as I can squeeze in - if I knew the person I'm speaking to wouldn't mind.
This is how I have conversations in my own head. Often it's a sentence with a LOT of English - maybe even mostly in English - with only a smidgen of Welsh because that's all I know at this stage.
What stops me having these conversations with a real live person is a concern that they might think I'm defiling their language by switching back and forth like this. But I feel that if I wait until I'm confident enough never to need to switch to English, then I'll be waiting forever...
Can anyone else relate to this? Could "all Welsh, or nothing" be a reason why more Welsh learners don't take the plunge and try out their Welsh in a real Welsh-speaking community?