Hi Lucy, I have the same machine with the same problem, I have taken twenty two pence in small change from the filter but still have a small leak when using my normal cycle. I'm about to try and do a self fix using info from this site. In case you have not come across the details here they are.... at least you wont have to pull the machine out... and best of luck with you imminent arrival.
This is what I found on the site
LG Washer leak fixed
On the front of the washer at the bottom, behind the square panel, is the access to the pump filter. (Water will escape when the large screw cap is undone). There is a rubber o-ring which keeps the water from escaping through this cap. In my washer, small amounts of water were leaking through this cap during the wash. There was no leak unless water was under pressure during the wash.
I put teflon plumbers tape under the rubber o-ring. I separated the cap into two components by prying it apart with a screwdriver. I cut a thin piece of plastic from a CD cover into the shape of a small circle to use as packing between the two components of the cap. In this way the o-ring provides a tighter seal. Also the areas where contact is made were cleaned.
As far as I can tell this has fixed the problem. Possibly the drawer was leaking also - as described previously.
J Hamilton, November 2009