Thanks for the advice. I plan to check in 4 hrs before departure.

And you would be surprised about that. Air cargo is a royal pain in the backside... first off you can't deal directly with the airline (ex-USA) you have to use a shipping agent (since 9/11, thanks osama). A shipping agent is going to need a whole lot of customs paperwork whereas with excess it's simplified as your travelling with your stuff, you can go through the nothing to declare channel on arrival in the UK (with less customs paperwork in case you're stopped). It's half the cost of Fedex (25% the cost of DHL!!) and only a few pounds more than cargo so excess baggage is the way to go. Best of all the stuff is in the plane with me on a direct flight rather than fending for itself at some shipping warehouse.