That Baukjen skirt looks like you'd have to do some careful rearranging as you sat down, so as not to bare both legs and flash you knickers, but apart from that, if you have the figure, and with the right top and shoes I could see that working. At a push, but it would def be informal.
I don't mind the style of the dress, its a classic cut and I can see being in jersey would make it less formal. But I hate the colour and the print, very mumsy and frumpy. You could find better in the same style.
If you like Baukjen, I have the Jersey Drape dress, and it has proved very useful as it can be dressed up with heels and big jewellery, or made more casual with flats or wedges and more understated jewellery. I have it in black, but the bright pink or cobalt blue are available in all sizes, whihc would be lovely in summer. It's double layer jersey and the ruching can be rearranged to hide or flatter where needed, the top can def be moved aside for bfeeding, and the jersey material won't make it too dressy.
www.baukjen.com/uk/shop/baukjen/dresses/jersey-drape-dress-quartz-grey.htm