American English generally uses /ʌw/ (main vowel the same as in “uh”). In Canada, as well as the northern US (and probably Northern England and Scotland) it’s more like /ow/ (main vowel as in “oh”. In RP, you’ll hear something like /əʊ/. In Canada, /ʌw/ is an allophone of /aw/ in syllables closed with an unvoiced consonant: "out and about."