How you feed your child is your decision as parents, so all i can suggest is that you develop a flat stare, as if you wouldn't dream of going immediately to bottles and why is the other person being so ridiculous as to even think such a thing (this is a useful attitude in general I've found, everyone has an opinion on everything parenting related ime!)
I would wait a week or two before trying to express, simply so you have time to get into the swing of things. The more your baby feeds, the more milk you'll have the next day - hold that thought when s/he feeds more, it's very rare that there's "not entirely milk" and exceptionally common that the clever baby knows s/he's about to have a growth spurt.
Once you get used to your new life, pick a time each day when you express. That way, your body thinks that there's an extra feed at that time and your supply will adjust to cope. Don't worry if you don't get much, a pump is far less efficient than a baby. Fwiw I'm still feeding at 14 months and barely got 2oz. I know other people who've gone longer and barely got a drop; it's not an indication of how much milk there is.
I don't think anyone's ever noticed me breastfeeding apart from the one time i tried to faff with a scarf (thanks, insecure mother when ds was a week old
) just be careful with clothing - a button up shirt or dress, a loose-ish tee shirt to pull up over a vest (to hide and keep warm your tummy) which you pull down, or both h+m and mothercare do cheapish feeding tops (£20 for 2) with easy access.
In the early days, feeds can be up to an hour or so long - make sure you've got a drink, food and the tv remote to hand! - but get shorter as the baby's mouth gets stronger. By 9 months we were at 20 minutes twice a day, even though at 1 month it was roughly 40 minutes every 2-3 hours. Milk production is highest after midnight so don't be surprised if you baby wakes several times to feed before dawn - ds regularly slept 8-2, 2:30-4:30, 5-6 having fed solidly (cluster feeding) from 5:30/6-8pm.
Comparing experiences with formula feeding friends, we reckon they're actually about the same amount of work over all, but with breastfeeding almost all the work is done in the first 3-4 months. Bottles still need to be cleaned and prepared at 2 years, while i just whip a boob out a couple of times a day. That said, if you're really struggling to breastfeed then formula is not a failure. The right thing is to feed your child, delivery method is secondary to that 