It may not be an issue for you, but I nursed a year and if I missed pumping as many times as I should've for more than one or two days i could tell in the feedings that it effected my supply, even with the older baby. It may be different for you, I have no idea. My input is just what I did and it was what I needed to do for me. I worked in a physical therapy clinic ( I'm in the US, I forget what you call it in th UK) so sometimes my patients ran over and such wherei would skip a pumping session. It wasnt the end of the world, but like I said, I did extra pumping at night to try to keep the supply going and to keep collecting the ounces that I should've to keep the balance for the times when I wasn't at work and was at home nursing ( I worked part time, three days a week)