Out of hard drive space - what do I delete?

Just finished a wedding edit in HD. Copied timeline to SD and exported to hard drive. Only have 3 GB space on my laptop. Which files do I delete which won't leave me requiring to re-edit or make a second export file? My thinking is to go for the render files from the HD edit sequence and render them another time if need be. Would this affect the SD sequence? I thought that I'd be able to get away with 143 GB for a two hour wedding sequence using Sony EX1 (2 x 8GB and 2X16GB cards). I've tried to back up all the files to an external hard drive but always get "error code 0" with one particular XDCAM sxs card file.
Any advice greatly appreciated. As I write I'm trying to burn to disc but I expect that lack of hard drive space will bring it to a grinding halt.