Is your lecturing job in the same place that you are doing your PhD??? If so there are clear Hefce and UCU guidelines on what your dept can reasonably ask you to do. If you have *chosen* to take on a lectureship at different institution whilst still completing your PhD (if for example you didn't get funding, or your funding ran out) the average attitude would be 'tough, you are lucky to get a lectureship, many don't. If you are finding it difficult, take an interruption of study - many people who try to juggle the two have to'