The deal was that Dawn would give them the baby and get £1,000 a month whilst pregnant, which you might do if someone was doing a surrogate for you, but May and Rob also offered £10,000 upon handover which would mean that they are buying the baby. May is just saying that Dawn is doing a surrogate for them to make the locals think better of her, as you wouldn't want to be seen buying your husband's baby and especially not with the reputation that she has.
I'll catch up with the later part of the week a bit later. I liked the way she was trying to seem nice by beeping the car horn, but being nasty by smirking and not really doing anything to stick up for Ben.