Like others have said, the issue with 2000 AD recommendations is everyone's will be different. Even key characters will result in heated debates about whether (say) Rogue Trooper is in fact dreadful or amazing. I'd echo previous recommendations in that the most obvious thing to do would be to start a subscription from the most recent jumping-on Prog, or the Christmas Prog (Rebellion's subs team may be able to backdate – they certainly used to when Forbidden Planet was doing this) and go from there. When you find stories you like, grab relevant trades.
As for the Hatchette 2000 AD collection, I guess that comes down to how much cash you've got to spend. It will include the bulk of the biggest 2000 AD characters (all of Nikolai Dante, most of Strontium Dog, seemingly all of Slaine) and a grab bag of other bits. There are some omissions that sting a little, but for the most part it's a strong, affordable grounding in some of the best 2000 AD series. The books are also really lovely hardbacks, too, which helps (and good value at £10 each). Notably, they are also being broadly released in reading order, so you don't end up hopping about continuity and wondering what the hell is going on.
As Blue Cactus said, the only downfall is a lack of Dredd (three books out of 80 is the plan), if that matters to you. On that side of things, you could always keep an eye on eBay and Facebook for people offloading their Dredd Hachette collections. That series has some duff moments, but has mostly been really strong. It's certainly worth grabbing if someone's selling their entire collection for half price or less, and you have the cash available. (You could probably also resell without loss. I managed that with the Marvel collection, buying the first 60 off of someone for 250 quid, and then selling them for the same price about three months later.)
