If you can do your own service work, ie, change spark plugs, engine oil and filter etc, check gearbox oil level, then you will be able to renew the cam cover (some of us "oldies" might call it a rocker cover) gasket. I've used both genuine and generic made examples and had no problems with either. It's not at all unusual to find this rubber gasket leaking when it's older and it can easily run down both the sides of the block and the top of the gearbox and down the bell housing. As suggested above rub some off on your finger and "sniff" it. Rotten eggs smell and it's gear oil, engine oil sometimes smells a wee bit like washing up detergent and is always less pungent than gear oil. If you decide to do the gasket apply some liquid gasket to the corners where it goes over the cam at the front and the rear. Sometimes it will leak if you don't do this. Oh, and clean the oil away with something like brake/carb cleaner or the sealant win't stick.
As Dave mentions above, the seal on the selector shaft can leak. The one on my boy's Punto leaked gently away for over 2 years before I did anything about it! Just topped it up with probably less than a small teacup full of gear oil every 6 months or so. Generally if this is leaking the oil goes down the back of the bell housing and dribbles onto the inner driveshaft joint so when you check it you think "smells like gear oil, inner driveshaft joint is wet with it, must be driveshaft seal" Of course it might be but look carefully at the selector shaft. It's higher up on the top of the box, so if it's wet it can't be being caused by the shaft seal. Unless you're dead unlucky and both selector and driveshaft seal are leaking! It's not a horrendous job to do the selector shaft seal but if your skill level is at the Oil and filter/spark plug/brake pad renewal sort of level you might find the selector shaft seal a bit challenging and you will need a rather better tool kit - pin punch and the like. If you do decide to give it a go be very careful not to drop anything into the box whilst you've got the top off! Cover it with some large old rags etc. The picture of the bell housing you've posted shows the front of the bell housing (I can see the coolant pipe) so my bet would be on the cam cover gasket being the culprit. If so it's so easy to do you might as well? If there's no oil leaking from further up but there is oil round the bell housing as can be seen in the pics, it could be a rear main crank seal - but this is not nearly so likely as the cam cover leaking.
Good luck and do keep us informed
Jock
PS our Panda's shield rattled too so I fabricated a bolt on clamp arrangement for the bottom after the nuts sheared off. Luckily the top bolts came out Ok but the holes in the heat shield were severely cracked and over large. I used two penny washers, one either side of the shield to secure it nicely.