That url is for the 320kbps webstream which can be captured using ffmpeg with the following command:

ffmpeg -y -i "http://a.files.bbci.co.uk/media/live/manifesto/audio/simulcast/hls/uk/sbr_high/ak/bbc_radio_oxford.m3u8" -c copy -t 06:00:00 C:\Radio_recordings.ts