Speaking from a student's perspective, you can definitely make a difference as a first year, especially on night shifts. Night shifts on postnatal ward are a special brand of hell - not enough staff and buzzers going all night with not enough time or people to answer them. I've only ever done one night shift on postnatal ward and it was hideous. As a student I'm not a proper member of staff yet I was told they didn't know what they would have done without me.
Anyway, enjoy it as much as you can. Focus on the basics - learning how to do obs, listening to the doctor's ward rounds, starting to help with breastfeeding support, nappy changing, giving women washes, helping them to the toilet etc. We're quite privileged as students on postnatal ward actually, particularly in the early years, as you have the time to do basic care. Having said that, you can sometimes be used as an extra health care assistant which is fine for some shifts but not all the time. You're essentially there to learn so make sure you're not just used as an extra pair of hands all the time and you are getting some teaching. Don't be afraid to get stuck in early on - help with the drugs rounds, get your mentor to go through the drugs cupboard with you etc. Make friends with the MCAs - they know all about baby care and some are better at breastfeeding support than some of the midwives. Don't worry if you're overwhelmed - it was so busy, I didn't have a clue what was going on half the time in first year.
I don't mean this to be negative but enjoy being a first year. I've loved postnatal ward as a student but in third year when I was given my own bay of women I felt constantly harassed and people will get stroppy with you because you haven't done their discharge paperwork or they've waited 5 hours to see a doctor. Sometimes you will have to tell a woman whose baby is on SCBU that she can't move out a bay full of babies because there is nowhere else to put her. You will feel terrible but having to deal with anxious parents who are desperate to go home and telling them they can't is a skill you need to learn quickly (I once had a girl with dangerously high blood pressure ask me why she couldn't just go and see her GP. Her family got very grumpy with me because I said she couldn't go home. I had to explain why without frightening the life out of her, i.e. she could have an eclamptic fit and die). Sometimes you will have to do hands-on breastfeeding support - hands-off is the ideal but when you've got a screaming baby who hasn't fed for 6 hours, your principles have to fly out the window. I'm not saying just shove a baby on the boob but ask nicely if it's okay if you touch them so you can help get the baby latched on. I've never had anyone say no.
You will forget to do things. I've had women before now ask me to get something for them then caught up in something else and realise 3 hours later I completely forgot to do it. A notebook will be your best friend - get used to writing everything down, when obs are due, drugs etc. because you will forget stuff. Sometimes you just can't provide enough care (although that's not so much a problem as a student but it can sometimes be) and you will go home feeling crap but you just have to try and do your best. On the odd occasion, you will go 8 hours without going to the toilet or having a drink. My mentors have been very good at making sure I have breaks but it does sometimes happen that you don't get one, or you don't get lunch till 4pm. I've only ever done 1 night shift and I didn't get a break at all. From a learning perspective, I would try and avoid doing night shifts on postnatal. The staff there won't have the time to teach you, and I think you'll have more learning opportunities from the day management of the ward and doctor's rounds (of course, you will see doctors at night but not as much).
You will find yourself wanting to scream sometimes. Visitors in particular take up a lot of time having to let them in and out and trying to fight your way through them just to take a blood pressure or empty a catheter. The endless paperwork and having to write the same things down in a hundred different places will make you want to slam your head into a wall. When I first started on postnatal I thought the midwives were all miserable bitches but by the time I got to third year I understood why. I was shouted out for no reason by the co-ordinator once and I was upset but I realised the ward was full and she was stressed. You will be snapped at sometimes by staff and you have to try not to take it personally.
Having said all that, I love postnatal ward. It is hard, physical work being on your feet for 13 hours and your feet will be killing you by the end of the shift. You will be frustrated that sometimes you don't have the time to provide all the care you want to but when someone hugs you and tells you you've made a difference just by sitting with them for half an hour teaching them to hand express, it's the best feeling in the world. I actually prefer it to labour ward - a lot of the students are obsessed with births, but I love getting to know women and helping them become more confident in their role as a mother. Good luck! A fortnight isn't very long but you'll be amazed at how much you can learn in such a short space of time.