Hi, I don't really believe in them as think those they've worked may have gone on to have their baby around the same time anyway. More say they don't work than do. I think there's enough prodding and poking when you're pregnant and give birth let alone letting the midwife fumble down there before the baby arrives. Mind you I was 2 weeks over due and had to be induced so always wonder if I hadn't have been so stubborn and had it done would it have worked!?!
Nope. Sweeps will do nothing unless baby was about to come anyway. At 38 weeks you still have a very normal 4 weeks to go potentially so I would just focus on your end date of 42 weeks and not be worrying about what thing you can do to force baby to come before it's ready.
They won't usually sweep you till 40 weeks unless you are about to be induced anyway.