To be fair PurpleDaisies "What's the worst that happens the ? He cries a lot and then you come home?"
You don't know that, do you.
My kids have 10 God parents between them. All lovely, great people, mostly chosen because I thought they would be good God parents, and one because she is a lovely friend who has no kids, was very supportive and I felt it would be good for her. I don't see all of them that often and there are about half who would probably not be great babysitters for my kids.
Parents need to make their own choices about who looks after their kids. being a God parent is not necessarily someone who will look after your kids.
"I know you're all right! I'll speak to DH when he's home and see if we can arrange a Saturday afternoon and just start with an hour or so away or something" Great, if that is what you want to do. I am sure baby will be fine but if you decide not to, that's fine too. You don't owe your friend a 'time' of looking after your baby! BUT if you value her offer, and enjoy the time she is willing to look after her Godson, that is great.
Re "When I tried to give my MIL some tips on his feeding, sleeping arrangements etc she told me she'd raised two children & didn't need telling what to do."
Yes but when I was young I am pretty sure the advice re sleeping etc was quite different. Car seats were unheard of. Why should people resent being given advice. I hope when/if my kids have kids and they share their advice/concerns I won't throw them in the bin.
"When I returned he had left me a nice little present in his nappy which she hadn't noticed (which is ridiculous considering the stench!) plus she'd not fed him as 'she was scared he would choke' "
I rest my case
Babies are not hat easy to look after, they are noisy, smelly, scary, lovely, and most of all their parents get to say who looks after them!