Harvesting Dilema

Hi All
My friend has 4 plants flowering outside, 2 NL x skunk & 2 of my NL clones.
I haven't seen them for a while but my friend wants to harvest them as the temps are dropping here in UK, they've only been flowering 7-8 weeks.
The night time lows are getting to 5C (40F).
Is it worth leaving them to mature properly or will the low temps ruin them? we haven't had any frost yet.
I'm going to see them tomorrow and check out the trichs with my 30x jewellers loupe.

thanks for any advice.

thanks twistyman, will know more when i get to see the trichs.

Pics will be on the way

they have some blankets you can put over your crop overnight to help provide some relief from the cold. my uses them for his tomato garden when it supposed to frost overnight and i guess it works pretty well

Well, had a good look and took some good pics.
The NL x Skunk (the 2 on the right - less purple) are pretty much ready, gonna chop next Saturday.
My 2 cloned NL (the beutiful purple ones) need a couple more weeks I think.