I have an interview for a role which is 20 hours a week. The hours of employment were in the job advert and suit me in term time but during the school holidays I would like to do the 20 hours over 2 or 3 days as the job will not pay enough to pay for 3 children in holiday childcare for 5 days a week. Do you think it is acceptable to ask if there is any flexabilty during the Q&A part of the interview or wait untill I am/if I am offered the post?