Could you wear a loose fitting midi dress, and then wear black bike shorts underneath, and go somewhere private to feed the baby where you could hike the dress up?
Or else, idk if you can Amazon this in the UK, but would something like this work? I have the tank top version of this dress and it feels & looks much nicer than I thought it would. https://www.amazon.com/Bearsland-Sleeves-Maternity-Nursing-Breastfeeding/dp/B07T483MY4/ref=sr_1_6?crid=URX9Z9RW3JP9&keywords=bearsland+nursing+dress&qid=1688071064&sprefix=bearsland+n%2Caps%2C107&sr=8-6