Thanks ladies for your support. Have spoken to DH and kind of made up. He admits that he sees how that offering me a couple of hours time to myself as a present from DD (yes present, not treat) could make me feel despondent, thinking that it has to be a high day or holiday for him to do a bit of childcare on his own. We went to rhyme time, which was OK, and thankfully she fell asleep on the way home. So she's been left in her buggy by the back ddor which is open, so she gets a lovely cool wind blowing past as I don't want to risk waking her by undoing to cover and taking her hat off. As a consequence I'm cold, but hey I can put a jumper on in a moment and it's a small price to pay.
As for expressing, don't really get the chance to as she usually feeds every 2 hours, and sometimes it's every hour and half. But I might give in and make up some FF tonight or tomorrow night and let DH take over.
But she's quiet at the moment, so I'm going to put on that jumper and have a little chill out.