I would buy vests and sleep suits, no cardis or coats for now. You don't know what size the baby will be or what the weather will be like. They are most comfortable in all-in-ones, and definitely avoid anything with a hood, or anything that does up at the back.
Go for some newborn size and some0-3 months. Vests - probably buy a mixture of short and long sleeve.
What they wear at night will depend on the temperature of the room but there was no real difference between what mine wore in day and night for months!
Don't but anything too expensive in newborn size!! I spent over £100 on newborn vests and babygros from jojo maman bebe, washed them, neatly folded them.....and then had a big baby so had to sell them all on eBay for about 2p. Boo hoo.
I'd get 6-10 sleep suits (aka baby grows) and the same of short sleeved body suits (aka vests with poppers). In hot weather mine just wore a vest and a nappy. Size 0-3 months. If you have a very small baby then send someone out to get smaller sizes. Both of mine were about 5lb and were in 0-3 by about 3 weeks. Cardigans are useful, 2-3 will probably do. You'll get bought lots of stuff: keep all receipts even for things you buy, and don't wash or remove any tags/ packaging till you need them.
what bonzo said is what i agree with. 6-10 sleepsuits and 6-10 popper vests is perfect. They tend to come in 3packs so I got 9 of each in newborn and that was easily enough. Do not spend lots of money on newborn as they will be outgrown very quickly. Just get the supermarket stuff. Unless it is very warm your newborn is likely to wear a vest and a sleepsuit at night. If it is colder you add a baby sleeping bag or blankets. If you want to swaddle your baby then you may need to remove the sleepsuit if it is warm.
For a late June baby you may need a top layer for going out for walks in the pram. I would just buy one light knitted jacket and one little cardigan in newborn size in case the weather is rubbish. Don't remove the tags till you need it and if it doesn't get used, exchange for a bigger size that you can use in the winter.
It is up to you how you dress your baby in the day. Many people just find it so much easier to stick to vests and sleepsuits. Babies sleep in the day after all. You will certainly get bought some outfits in 0-3 as gifts and these are nice to use if you want to dress the baby up a bit to go and meet granny or whatever. Often they are hopelessly impractical though.
If the weather is particularly warm you may want to buy romper suits with short sleeves and short legs. I had a couple of these in 0-3 and they did get used in June and July even with the crappy summer we had last year. If it is hot enough to dress baby in one of these, you won't need a vest underneath it.
For the bodysuits and sleep suits, would definitely go supermarket. George was brilliant, washes really well.
Would definitely buy some newborn though, as any presents you get will always be bigger, and we actually had to go out and buy more newborn as we were over cautious, had lots of leaky, up-the-back, nappies, and no tumble drier!
size 0-3 months hung off my 7lb 13oz baby, so I was glad for a few "newborn" vests and sleepsuits. Newborn stuff lasts for a month at the best, so let that influence your spending! You can buy as much 0-3 month stuff as you like because they'll eventually need it.
Most babies don't like getting dressed so I didn't bother with proper clothes, just vests and sleepsuits. Within the first month or two I was out in the evening with baby so a few warm cardigans will come in handy. June can be cold!
I would second the supermarkets, they do have some lovely clothes and are very reasonably priced.
Some people swear by sleeping bags - we used one when baby could wriggle bed clothes off and it was fab. But I won't be using one with my second baby until he wriggles.