Just joined (first post) but after having my fan belt snap last week, I noticed a lot of oil around the O/S drip tray, bottom corner of block/sump and around the crank pulley - turns out to be the crank seal. Apparently it's common enough on them.
If your a competent enough DIY mechanic the oil seal is only £7-15 (if you shop about) but you might want to consider a new belt while your at it (maybe even change the tensioner but I didn't bother, mine was fine...)
🙂