I think it all depends on whether Ancic is fit or not - if he's not then I'd definitely go for grass, otherwise maybe a slow hard court?
I think Ljubicic should win both his singles and then it depends on whether Ancic is fit or not. I'd back Henman to beat Karlovic but not Ancic. I'd back us to win the doubles though as they haven't got any doubles specialists whereas we have Jamie Murray.
You don't think that Murray would be capable of beating Ljubicic on a slow hard or grass court? Both bad surfaces for Ljubicic, but especially on a slower court, Murray would probably be able to grind out a victory due to the longer rallies.
Yes I agree with you about Ancic/Henman. Ancic beat a much healthier and younger Tim at Wimbledon, so I doubt Tim would fair any better now...