Howdy Dowdie - Go to google.com and type in "I must away love", including quotations. You'll get a plethora of links including one to this:
Cheers, Bardford
THE NIGHT VISITING SONG
         Recorded on 'Half Ower, Half Ower tae Aberdour'
         by Jack Beck
         The Tradition Bearers - Scots Songs and Ballads Series LTCD1006
         "I must away, love, I can nae langer tarry,
         this morning's tempest I have tae cross,
         I must be guided without a stumble,
         intae the airms o' my ain true love".

         And when he cam tae his ain true lover's dwelling,
         he knelt doon gently upon a stane,
         and through the windae he's whispered gently,
         "is my true lover within at hame"?

         She's raised her up from off her down-white pillow,
         she's raised the blanket across her breist,
         and through the windae she's whispered gently,
         "who's that disturbin' me at my lang night's rest"?

         "'Tis I, 'tis I, love, it is your ain true lover,
         please open the windae, and let me in,
         for I am wet, love, and unco weary,
         and I am near drenched untae my skin".

         She's raised her up from off her down-white pillow,
         she's raised the windae, and let him in,
         and they were locked in each ither's airms,
         until the lang night was past and gane.

         And when the lang night it was past and over,
         and when the grey cock began tae crow,
         they've baith shook hands, aye, they've kissed and pairted,
         he's saddled and mounted and away did go.^^^