I've already got a 1st gen iPhone, and I'm in London. O2's entire network sucks - it's not limited to EDGE or 3G. I can get no signal in places inside my flat in Central London. Then I can swap the SIM for a T-Mobile one and get full signal (unlocked phone).
I think the speed issues are overhyped. I'm often on EDGE once outside, and the speed is fine. No, it's not broadband speed, but seriously - you're on a phone. Probably just checking sports results or the news. You're not downloading torrents. You don't need much more than EDGE for a mobile. And then you have WiFi access for when you do need something faster.
The current iPhone is fine. I don't see the lack of 3G as an issue. Of course, you'll probably get a good deal on eBay if you do wait for the 3G model to be announced, and then you can see what else, apart from 3G, is being added to the new model (GPS looks likely, looking at iPhone OS 2.0).