Weed killer before sowing grass seed
I wondered if you would mind offering your advice on weed killers for lawn establishment purposes? We're getting our garden dug over in a couple of weeks and the gardener we are bringing in had plans to weed kill the soil, and said we could plant our grass seed for the lawn a week later. However, online I've read that this can kill off earthworms and other insects etc. so I opted against using it.
I've just been reading up on wildflower establishment and a professional gardener was advising to use weed killer in the soil again before sowing the seed. I've found conflicting advice online as to whether it's a good idea to use weed killer or not, and how bad it is for wildlife etc so thought I'd check in here.
Thanks for any help and advice,