I don’t think it’s a North South thing.
Ga i fynd i’r tŷ bach? Is what we always said in the Rhondda.
Half the issue is children barely use Welsh outside of the classroom (in the valleys) so the majority of what they do is formal. There is no community language as such. When I started learning, I used to listen to my daughter who was in welsh medium education. It was the worst thing I could do. 
Oh dear Neil, at 75 years old & living Glocestershire all my life I am struggling to recall English words - never mind anything else BUT that phrase you gave as an example will be VERY useful to me when I next visit Wales! 
Thank you.
Thanks for solving the mystery for us!
I have the impression that the girls are looking at things from a common point of view of children and teenagers: "we’re young and we’re learning now, therefore we’re modern (and usually right). And if mam, dad, mam-gu and tad-gu say something different it’s CERTAINLY because they’re old-fashioned (and often wrong)! 
In any case, I’ve just had a look at the books from the classic Welsh courses for adults (southern Version - downloadable on line), and they teach “Gaf i”.
But I’m sure on SSiW Southern version and @garethrking’s book I have here, it’s “Ga i” instead. So probably more of a specific teacher’s preference or specific town/area maybe?
I just can’t help adding an off topic note about how funny it would be ordering this (very good, by the way) wine from Piedmont over there! 
“gaf i” is the ‘book form’ (‘proper’ Welsh) and “ga i” is the spoken form (all over Wales, not just the South).
It’s a school thing I think - we’re so often taught to speak the ‘proper’ languages rather than the spoken ones (think “do not know” vs “don’t know” or “dunno”!). I’m not saying it’s not important to know the ‘proper’ language, but unfortunately some teachers don’t mention that that’s sometimes not what people actually use in everyday speech!
Although, having said that, I do recall many native speakers from our village (about ten miles SE of Aberystwyth) routinely saying (as it sounded) Gaf i - but it’s not that they were being very ‘booky’, they were using the fi pronoun after the Ga - so really they were saying Ga fi rather than (literary) Gaf i.
This is so true, @rosemaryburgess. Sometimes I forget a word when I am speaking Welsh. A helpful person says “Well, what is it in English?” I say “I can’t remember!”. With luck it will come back half an hour later.
Back on topic, I have just done a session of an online course, and the main focus of the session was using “Ga i”.
Sue
Wow, that’s a coincidence Sue - a pity I was not signed up to that one. Never mind, we 'hen merched ’ will get there in the end. Diolch yn fawr. 
I’m sure you are right Gisella - I’m off to the shop to say “gaf i potel Gavi, plis” Cheers!
Thanks Sharon
Thanks Emma, so long as I say it with a smile I think I will be OK!
Co-incidentally, the 1st language facebook group, Iaith, has just started a parallel discussion. It’s obvious now that it wasn’t the case, but they are mentioning a point that I was too nervous to suggest -
Some dialect speakers are using alla’i cael? (Can I have?). It doesn’t seem to be going down too well in some quarters 
By gosh John, this trying to learn Welsh is a linguistic minefield! I’m not into facebook any more, you are obviously made of tougher stuff, but thanks any way. 
I always try to find the shortest form and stick to it, it’ll blow your mind otherwise 
Very sound advice Neil, diolch yn fawr.
Ga i is fine.Its polite ! 
Diolch yn fawr, David
