If you've already got the turf, it's important to lay it as soon as possible, so don't wait if you have it. If you haven't got it yet, wait till next week or the week after - in London, I'd do it now, but where you are, it'll be colder for longer I'd guess. A bit of light frost won't kill it, but if you laid it now, it'd just sit there for a while till it warms up a bit and then start doing its thing, so better to wait if you can till the temperatures not below 5 degC at night.

cheers havent got turf yet will wait a couple of weeks probably not make a difference to growth any way