Found a better way to iterate over the rows (although I still feel like I'm reapting myself!):

for idx, row in enumerate(active_sheet.rows):               
    for i in active_sheet.rows[idx]:
        values.append(i.value)

And instead of converting the tuple to a list:

rows = [list(t) for t in zip(*[iter(values)]*column_count)]

Found a better way to iterate over the rows (although I still feel like I'm repeating myself!):

for idx, row in enumerate(active_sheet.rows):               
    for i in active_sheet.rows[idx]:
        values.append(i.value)

And instead of converting the tuple to a list:

rows = [list(t) for t in zip(*[iter(values)]*column_count)]