Philippa,

Sorry if I sent you on a wild goose chase. I found Abair amhran and the song wasn't in it, but it was in another song book called Amhrán-leabhar Ógra Éireann which I bought in school when I was 10. The song is listed as a translation (to Gaelic) by Diarmuid Ó hAllmhain. Looks like he also transposed it (geographically rather than musically) to the west of Ireland from the isles of Scotland (unless there's an equivalent text in English, which I've never come accross).
Here it is :

Air: The Road to the Isles

Tá an mhuar-fharraige 'om gairm féin aniar,
'S mé ag imeacht romham im fhánaí tríd an sliabh;
Gura buan a mhairfidh mé go bhfaice mé mo mhian –
An t-oileán órga áileann Inis Thiar

Chorus :

O ! trí aiteann is trí saithnigh is trí fraoch atá mo thriall,
Thar carraig is thar portach is thar riasc,
Is má cheapann tú gur amaid mé nó streare bocht gan chiall –
Níor airís géim na mara fós aniar;
Gura buan a mhairfidh mé go bhfaice mé mo mhian –
An t-oileán órga áileann Inis Thiar

Bím ag síor-thaiasteal liom gan sealadh sos ná scith,
Trí dutha ghlé an tSeoigh ag imeacht siar,
Trí crích í Fhleatheartaigh ag tarrain ar na dTonn
Go srise mé fá dheoidh Inis Thiar

Translated by Diarmuid Ó hAllmhain

An approximate translation to English (by me)

The roar of the sea is calling me westwards
As I travel as a wandrer through the mountains
May I live long enough until I gain my desire
The beautifull golden isle of Inisheer

Chorus
Oh! I make my trail through gorse and through ? and through heather
Over rocks and over bogs and over ridges,
And if you think I'm foolish or a poor senseless rover,
I still haven't heard the leaping of the western sea
May I live long enough until I gain my desire
The beautifull golden isle of Inisheer

I'm always travelling without pause or break or rest,
Going west through the beautiful Joyce country,
Through the territory of the Flaherty's I'm drawn towards the waves,
Until I finally reach Inisheer.