Is there a threshold I need to keep in mind or is it one of those depends on the item type duty situation like other countries?
My average package value is sub £200 and only really go over that sending to some distributers a few times a year (but think about it they are in the US and Japan, so not an issue).
There are thresholds. I am not entirely certain what they are, but suspect they will be more than £200. It is worth checking on the HMRC website, though.