'Hoffi' is the standard verb for 'to like' and is used all over Wales and specifically in the most commonly used Welsh for adults teaching course. 'Licio and Lico' are local variants of hoffi. 'Hoffi llefrith' would be in the North Wales course and 'Hoffi Llaeth' would be in the South Wales course.
Where would this question be said quite like this? As I recall from SSiW, the northern course taught "dach chi'n licio llefrith," and the southern course taught "ŷch chi'n hoffi llaeth." This is sort of both and neither, and I'm wondering where and in what setting a person would say it this way.
hoffi and licio are both used all over Wales. Ydych chi ...? has many local variations, including dych chi, ŷch chi, ych chi, dach chi, dech chi...?. There is no clearly defined boundary between areas where llaeth and llefrith are preferred for 'milk'.
The 4-6 (depending how you define them) main regional dialects of Wales (there are many more local variations) have considerable overlaps in their boundaries, and the boundaries between various dialect words and patterns are not consistent. For example, see this - https://museum.wales/articles/2011-03-29/The-Dialects-of-Wales/. The idea that there are just two distinct dialects of Welsh with some sort of geographical boundary between them is wrong.
Somewhere in Wales somebody will be routinely using the form Dych chi'n hoffi llefrith?. Not too far away the usual form might be Ydech chi'n lecio llâth?
In this introductory course we can only cover a very few particularly common dialect variations.