Another oil leak question

Hi guys my 300tdi has recently been leaking badly at one point last month it used nearly a litre of oil in a 300 mile round trip anyway this past weekend i have re sealed the sump and replaced the gasket on the rocker cover and sorted the leak on the oil breather andthings seem alot drier however she still seems to be leaking from the rear crank seal.
So what i want to know is how much of a job is it to sort with me being a novice at mechanics and all work is done on the pavement outside my house ,i dont mind having a go at stuff and have built up a fairly decent tool kit after 18 months of landy ownership so what do you rekon cheers for any help

you would need to remove gear box ,seal is in aluminum housing will need new gasket to and carefully cetralise seal before tightening bolts ,as there are no locating dowels,often leak between housing and block,get genuine or oe have had some warp and leak within days

Thanks mate will give it some consideration whats the chances that the seal will fail completley and leave me goosed at the side of the motorway

never come across that yet ,but anything possible ,but unlikely