Welsh is spoken by about 19% of the population, according to the last census. In South Wales where I live, the proportion is much lower.
A number of primary and secondary Welsh schools exist, where the complete syllabus is taught in the medium of Welsh, although if my two nieces are anything to go by, the language isn't used very much in everyday life, if at all. In North Wales, much more use is made of Welsh.
Children in Britain seem to pick foreign languages very easily and quickly, providing they are taught properly. Its when you get older that it becomes more difficult I find.