Varnishing the New Hive

Picked up my new hive this week from Thornes in Stockbridge. I had ordered a bunch of stuff, including a new hive and a traveling box, both of which I varnished today as it was raining all day; so not able to do anything in the garden or check on the bees. I use a very light varnish which is recommended by the supplier; I was not sure whether to use varnish or not, some beekeepers do, some say it isn't good for the bees. I decided to give it a go, it makes sense to protect the outside of the hive, but of course you don't varnish the inside where the bees live! I also picked up a plastic queen excluder to try... apparently the steel one I already have could hurt the bees passing through; I haven't seen any proof of that with the colony I already have, so I shall see how the new one works out. So I am all stocked up and ready for another colony of bees. I have got my name on the 'Swarm List' with the local Beekeeping Association; when a swarm is spotted, the local association is asked to send someone to pick up the swarm. This is only my second year, so still trying to get to grips with exactly what needs to be done every year.