i used to live near the tesco in hatfield, although i was a stones throw from stanborough lakes.
I had 20mb and would pretty consistently hit it at all times, maybe the odd small dip for peak usage but over night and such was always nearly spot on
i had cable there since it started years ago and its been extremely reliable and fast. i have the opposite issue, now im no longer cabled up and have to get DSL , i dont want to