I didn´t have endometriosis and I think that is likely to be the cause of some pain. However, a D&C is a very simple process - more like a heavy period than anything. Expect to feel the effects of the anaesthetic, pretty drained and fatigued, but otherwise very litle. The bleeding depends on you, once, with me, there was hardly any, the next time it was quite heavy, but only for a couple of days. I have had several of these procedures and there really is nothing to worry about.
When I had my coil inserted I felt a lot of pain ... everyone is different, but after the D&C I was fine. Relax, that´s the main thing, everything is worse if you are tensed up!
I´ve just seen your question re swimming. Ask your Doctor on Wednesday ..... and have a wonderful holiday!!