If you don't want the whole van set up, you can use my method (for dealing with loads of flats etc). Get the big blue tub from Lakeland for the racks (around £15) and I use 2 kettles to fill it on the custie's draining board with Dirtbusters Bio liquid and the bio boost powder. Leave it for half an hour and most of the crud comes off with a bit of steel wool. I also use the bio liquid to coat the oven interior when heated up a bit and then blade. Thinking of switching to the WOC bio though as DBs sometimes sends me quite runny stuff and it seems less effective. I don't think they do the bio boost powder though...