Annalise, the advantage of a childminder for your children would be that they are looked after together as siblings. In a nursery your baby would be in the baby room and your older son in the toddler/older childrens rooms.
I know for a fact from nursery nurses locally that the two children would not see each other, ever, during the day. At a recent training course it was suggested to nursery nurses about vertically grouping children ie family grouping, they threw up their hands in horror and said it couldn't be done. We asked if it was not possible for siblings to visit each other, the NN's said if they did that, what would happen to the other children in their care. A NN is also responsible for 3 babies under one, a childminder may only have 1 under 1 and 2 under 5 in her care at anyone time. I have a friend who has her two in a local nursery and they only see each other morning and night at delivery and collection time.
How can a NN give 3 babies undivided attention? I make sure that each child in my care has some undivided attention everyday, when the baby is sleeping, I do special things with the toddler and when the toddler is resting, baby spends most of her time on my lap with books, doing finger rhymes, talking, tickling, cuddling. just being a baby! In 4 months we have developed a very special bond, she is delighted to see me every morning when I pick her up from her house, we wave bye bye to both parents on her doorstep and she is smiling away,
I do think nurseries have a lot to offer for older children (2+) but feel strongly that a baby is better off in an home environment. They can sleep when they want to, eat when they want to, they don't have to be in the nursery routine.
I understand your concerns about nannies, but childminders are not nannies and cannot be compared in the same vein with" nannies from hell" type documentaries, designed to scare every parent out of their wits about their childcare choice.
Most childminders are mums, nannies are not, mums have been there, got the experience and can cope. We are fiercely regulated, I spent 3.5 hours with an Ofsted inspector this morning, who turned over every stone and opened every cupboard, lifted the loo seat, checked my cot linen, locks, sheds, carseats, pushchairs etc, and the asked about my routine, what I cooked etc.
I told her about going to the farm to get the meat, seeing 20 minute old lambs, going to the fish shop, 'Peter the fish,' getting out giant fish for them to look at, and I mean huge halibut and tuna 3 feet long, choosing our fish etc.
The inspector had worked in many nurseries and said, you cannot however hard you try, recreate those experinces in a nursery. The children went out once in the three years she worked in one. No puddle jumping, leaf kicking, duck feeding, library visits, trips out to lunch, visiting friends, swimming, we even take our little ones sailing ( see pic on my website) and as my husband flies, to the local airfield to explore the planes.
Okay, most people know how passionate I am about childcare, so I'll get off my high horse now and wish you luck
Wesbite for childcare and nurseries by postcode search, and look for someone who has been part of a quality assurance/ standards scheme -kitemark in childcare here