I would help you since I was raised and still living in Ireland... but I know feck all Irish since I got exempted for being born in a different country. I know how to tell some one to kiss my arse, call them an idiot and that's about it sentence wise. =B Not sure if you want Irish Gaeilge though...
Do you mean Old Gaelic, or modern Irish (which is also called Gaelic)? The differences are subtle, but important. (And I do not know a lick of Old Gaelic)
There are a couple of things wrong with the phrase:
"Adhaidh" is not correct. In fact, it isn't even a word, unless it happens to be slang in some obscure dialect I am unaware of. Your Google search proved to be useful, as "aghaidh" is a word, roughly meaning "face".
When paired with "ar", as in the phrase, the meaning changes to roughly "in front of", which can be interpreted as "ahead" or "onwards"
Do not let him use soal. In most languages, that isn't even a word; but in one UK dialect, it means "dirty pond". The word you are looking for is "saol", which means "life".
Otherwise, as someone else pointed out, "leannan an saol ar aghaidh" means, roughly, "a lover of life ahead", which can be localized in English to mean "life goes on".