Hey
I can't say too much about this set as this is 'proper old' Lego so a bit out of my area which is more 99 onwards, I do know this set was released in 1976 and that is the European box version. I don't think these older sets come up for sale that much, but I wouldn't say that equates to extreme value, my guess is maybe £30-£40ish and the market for these sets is very, very, very small, so eBay may not be your friend on this one.
There is a chap called Gary Istok who is a walking Aalmanac for all things Lego vintage and if you are a member on brickset (or join up) he would probably be able to tell you all you needed to know, that forum may also be a good place to go for a valuation request, maybe even a sale, it is the best and one of the largest Lego communities out there.