In an ideal world you wouldn't need one really unless you were planning to express, but for me it was an essential piece of kit as it turned out. I bought the tommee tippee manual pump before the birth as i felt i couldn't justify the expense of an electric. We had lots of problems breastfeeding from day 1, and at a few days old when he was screaming with hunger and i just couldn't get him to latch on all day, and had been trying for HOURS, we eventually expressed and fed him with a sterile syringe. I had tried hand expressing but couldn't get any, so having the manual pump in the house was a lifesaver. If we didn't have it my hubby would have had to go out at 11pm and try and find one in an open pharmacy, which would have added a lot of extra stress to the situation. The manula one was pretty useless though, and after a while when we were still having to use it regularly we got a medela swing, and then when i had to go to exclusive expressing we hired a hospital grade one from a breastfeeding centre. When i bought it i wasn't sure if i would use it, but i was very glad to have had it, so personally i would recommend getting one... but that's probably just from my experience. If I had had an easy breastfeeding journey and not needed it then i'm sure i would be saying the opposite!
Can you buy one and keep it unopened and the receipt and return it if it turns out you don't need it?

Good luck!