Mentally, try not worry, both my elective sections were calm and pleasant events. You are in the hands of a team of people who know what they are doing and have a plan to deal with any variation from a straightforward c-section. A midwife is in theatre waiting to take care of your baby once it is born. You are not at the mercy of the system of one midwife looking after several labouring women at once and hoping she will be in the room with you when you need her.
Prepare yourself for a 6 week holiday from all housework once you have had your c-section. Organise for a relative or friend to hoover for you if it really bothers you. Let your dh know now that you will not be doing housework for 6 weeks so he can't say he wasn't warned.
How old is your ds ? I trained my ds to climb into his bed himself and in and out of the bath, sorted out appropriate steps/handily placed stool etc and let him practice so I wouldn't be tempted to lift him post section. Ditto with getting in and out of his car seat. I talked about not being able to lift him after the baby came and needing his help to fetch nappies etc.
On a practical note, buy some Big Knickers, plenty of them, the kind where the elastic comes up to your waist, instead of being around your hips. Other knickers will rub along the scar area.
General stuff for having a second child.....
Prepare some meals and put them in the freezer, stock up on loo roll and washing liquid. Sort out internet shopping if you don't already do this for groceries.
Can you afford a mothers help for a couple of hours a day. it was a luxury but really helped me loads.
Buy some thankyou stationery and stamps ready to acknowledge gifts and if appropriate get some birth announcement stuff ready too.