Hmmm...
I was a big stamp collector in my youth. I inherited my mother's massive collection along with my own, and it has all stayed on several shelves upstairs for a decade or so now.
If I was in your shoes, I would take it to a local stamp appraiser. Do not sell it to said appraiser, but get his/her opinion on the whole collection. I believe stamp collections are worth more as a collection and not pieced out...but I could be wrong on that. Once you have a starting point, than you can figure out what to do next.
The reality is that most stamps are not worth much unless they are in mint condition and not glued/hinged onto a page. The real worth of a world stamp collection is the learning and greater appreciation of other places, cultures, and people that you learn from their respective stamps. I highly endorse stamp collecting for children.
Sorry I can't be of more help Dunc. I only currently collect Canadian FDCs.