Hi
I have a colleague who is the same age as me(64)who travels all over Europe spotting numbers although this is not a route I will take I just want to get a decent knowledge of European Railways and their fleets.
Part of my family has been resident since 1949 on the Franco-Swiss border near Geneva, so although I am younger than you (51 this year) I have spent some part of all of those 50 years looking at rail-based transport (including trams my father is one of Britains foremost tramway experts) around Europe and beyond.
If you are starting out, railfaneurope is the obvious on-line starting point. It covers all of Europe (and selectively further afield).
http://www.railfaneurope.net/
It has two basic areas, pictures and stock lists, plus other useful pages covering liveries, numbering schemes for traction on various European railways, etc.
The stock lists area is the first place to go to check on the currently active and now withdrawn traction.
Each company has a good (extensive for the larger 'national railways' eg SNCF) intro piece describing the company and its network.
Note that the withdrawn category majors on diesel and electric traction so although it lists modern traction withdrawn as long ago as the early 1960s and 70s it doesnt go all the way back in history, for example steam locos are not included.
Nowadays, the lists include the national railway eg SNCF in France, but also all most local or private railways, track maintenance companies in fact any organisation that has its own traction.
Some experts complain that even this resource is not up to date enough but I dont have any complaints. It is a great resource, especially for newcomers to railways outside the UK. Despite my inherent expertise, I still look at railfaneurope frequently to check up or remind myself about any European railway subject.
Having said that, there are a few oddities and pedantry to beware of, for example in the SNCF (France) withdrawn classes lists. A one off prototype loco which ran in the Savoy Alps is listed in two separate places, first under its guise as number 10001 (listed as rebuilt as 20006'). It is then listed again in its guise as 20006 (listed as withdrawn 1971 its final withdrawal from service). Typical of the one or two omissions is that 10001 was actually 6051 before it was 10001 but this bit of its life is not included. Furthermore there are some one off temporary conversions listed in the withdrawn locos tables, but some of the locos of the class are still in service so dont be diverted by this.