shil can I ask you what it is specifically that you are concerned about? I ask because it can be useful to make a distinction between emotional and practical help.
I don't personally think it is very enjoyable for any new mother to be on their own without any family or other support all day, especially if you then are the only person on night duty (which if you are breastfeeding, you will be, and I do recommend looking into co-sleeping asap, or at least a bedside cot). tbh, if you have a small flat then a crying baby is going to wake you no matter who is caring for it at the time. In all honesty I think night nannies only work if you have a fairly big house and are formula feeding.
Of course plenty of women do end up on their own all day, and they cope in the sense that nothing catastrophic happens - but really, help is - well, so helpful, if you can get it.
If you can identify what help you think you most want, then you can try and plan. A cleaner will help you with the house but not with emotional support, or giving you a break. If your partner can't change his work hours, then negotiate with him so that when he gets home, he can take the baby for a couple of hours (this is his baby too) so that you can have a bath or cook a meal or whatever you WANT to do (go to bed!) without being primarily responsible for everything to do with your baby. If you are breastfeeding, your baby can be handed to you for a feed, but then taken off for a cuddle with daddy.
Find a mum and baby group near you. Go to it even if you are unsure at first. A change of scenery and listening to women in the same positon as you will do you a world of good. They will also be a MINE of information when your dc is older than a few weeks about what groups and activities are good, where is baby friendly and where isn't, etc.
Advice to stock up on very easy meals and snacks is spot on. Sky plus is your best mate, as are dvd box sets. If you can make a super luxury purchase, my personal tip is get a Kindle and an ipod touch! I got both when my dc was around 6 months - they should come in the Bounty bag for all new mums, IMO. an ipod means you can e-mail, surf the web and even order shopping with one hand (oh, and watch iplayer) - and a Kindle means you can read one handed without awkwardly trying to turn a page every 2 minutes, or dropping a heavy book on your dc's head (ahem).
If you drum up social support, don't assume every visitor will be helpful. Some are brilliant - distract you, make you laugh, then go and tidy your kitchen (without comment) while you nap for half an hour. Some sit on their arse eating your biscuits while you bring them umpteen cups of tea, talk about their problems for 2 hours and ask you what's wrong with the baby when he cries. You want the former, don't stress yourself with the latter.
FWIW, I think it's absolutely fine to think ahead and accept that the first few months of being a new mum can be tough. I'm not saying 'yes, worry about it!' at all. Just that I do hear first time mums to be talking about how they are going to (a) write a novel (b) learn a language (c) redecorate the house or (d) set up a knitting/cup cake business while they are on maternity leave. And I think - they have confused 'having a baby' with 'a holiday'. You are not falling into that trap!