The Hitman site says that the Silver Edition is US Digital only, but according to Steam in the UK, I can buy the Silver Edition.
Not sure why you would buy the Silver Edition to be honest. Not sure if other pricing is different, the UK pricing has standard at £45, Silver at £60, Gold at £70, meaning you can buy expansion 1 for £15, or both expansions for £25. Not to mention we know absolutely nothing about either expansion, so not sure why you would decide to just buy one when you know nothing about either.
Personally, I’m probably going to stick with the standard. Don’t have a huge amount of money on me right now, so will wait until I have some cash again to pre-order. I like the Sniper Assassin thing but not enough that I need to play it right now, it can wait. TBH I can’t imagine buying the gold edition will save you much money compared to buying the expansions individually anyway, and the reskin gun and suitcase do nothing for me.