That is good you are able to source Nuc in Lanstroth. Which in the UK are you based. I am now the treasurer of the club I belong to and our Beekeeping beginner course has already filled up.
I do not insulate the hive as it is not that cold in London. I am not used to the 8 frames though you don’t get cedar brood boxes in 8 frames in the UK unless you buy from FlowHive. I have bought some Pine 8 frame brood boxes and hives that I will use in swarm control. As long as the pine gives me 5 years minimum I would be happy with that.
I kind of like the 8 Frame hives, I have double brood and going to test and see if the bees do well with a third brood box. Though I can’t tell you how it will go till I do try it.
It does not really matter if you go for 8 or 10 frame as long as you then have all your equipment in the same format as it would make your beekeeping easier. Swarm control creating new colonies etc.
When I bought the FlowHive there was only Cedar, they are slightly lighter weight than pine. But do remember all wood does have wear and tear outside. I used Tug Oil on my FlowHive to keep the wood effect.
Have a look at come of the video I have done in my first 18 months of beekeeping. Hope it helps you learn from it.