For the first 4 weeks, forget day and night. It is perfectly reasonable to conduct most of your affairs in a milk stained nightie, and to order in pizza every night. For your lunch.
If baby is awake at 3am, you have to be awake too, so therefore it is acceptable that if baby is asleep for 3 hours between 11 and 2pm, you can be too.
Bare necessities
2 packs of 7 newborn primark vests - £8. Will need to be replaced every 3 months until 1 year old, and every 6 months after that.
2 packs of 3 Primark babygrows - £10. Ditto above for replacing.
2 cardigans from Primark - £10
Hats and scratch mitts - £10 total max
YOu also need
Blankets for the cot
a cot and a mattress for the cot
A method of transporting the baby (usually pram or pushchair - some go for a sling but a lot cannot cope with having nowhere to put the baby down ever and having to carry all equipment
Nappies - now, I know a lot of people sing the praises of washable nappies, but if you are on your own with a newborn I would strongly advise you to buy the second size of washables only and use disposables until you fall into a routine whenever your baby decides to do so. Babies poo a LOT at first sometimes, and you can quickly become exhausted on your own with no help if you run out of nappies.
Cotton wool for nappy changes
Nappy cream for nappy changes
Non biological washing powder for the baby's clothes, bedding, towel and nappies - if it's just you and the baby it's easier just to switch yourself over to non bio!
If you decide to mix feed or bottle feed, you need a steriliser, bottles and formula, if you know you will want to express and keep the milk, you will need the above and a pump.
YOu do NOT need a baby bath, a bottle warmer, a baby wipe warmer (or indeed baby wipes), special expensive 'educational' toys, multitudes of clothes, shoes until the child is walking around outside, crawler shoes, Baby Einstein dvds, £300 prams, matching nursery or any of that guff.
The baby needs food of an appropriate type, to have it's bottom kept reasonably clean and dry, to be kept at an appropriate temperature, and you. That's it.
If you are on you own, I advise you to get a lot of nice sandwich fillings in, plenty of bread, some nice juices (but include some prune juice in case you get constipated) and some paper cups and plate. Then you can kiss off cooking and washing up for as long as you like.