Big garden - typical costs for a gardener

[Amateurish]

We are moving into a new place in a month's time with a big garden. Neither of us want to spend any time gardening, so we are looking to get a gardener in. The vendors have given us their current gardeners's details, but I was wondering if other PHers with large gardens could give me an indication how much time their gardener spends per week and what the cost is? The garden is 1 acre with most laid to lawn. Lots of borders and flowers around. I would probably do the mowing myself. Cheers