Hello John and Ria,
First and foremost, WELCOME to the Garden Pond Forum! Wonderful to have you join us.
To your question on liner, I certainly would have no personal information regarding where to buy EPDM liner in your area. You'll want at least 45 mil thick EPDM liner for this pond. That is usually the norm.
Is there a google (or other) search feature for your specific area? Like Google.eu or something akin to that which would bring up search results from your region only? Beyond that, I don't think I am much help to you in this regard.
There are many opinions on how to construct a pond, and we probably have them all right here. We have garden ponds, indoor ponds, outdoor ponds, koi ponds, goldfish ponds, turtle ponds, baitfish ponds, ponds for elderly dogs with hearing and sight problems and now, with you, goose ponds!
Sounds so fun, it's giving me goose bumps!
I'd say the first thing in order is to start with what you believe you need or what you desire for your geese and then ask if the pond is going to be only for the geese and no other critters? Or will you be adding fish/turtles or other aquatic species in the future? How large of an area and how deep? Also, if it is going to be a pond for geese, I know firsthand that you are going to need a pretty good filtering system to keep the water clean. I have seen what geese can do to a 3 acre sized lake, they are not the cleanest animals in this regard. Then you need to address the expense you are willing to put forth for the pond. Depending upon what you construct, you can get into a large sum of money quickly.
I am going to assume that you desire it to appear naturally aesthetic so that it is a beautiful flora habitat as well and blends into the landscape.
With a little chat here and there, we will probably supply you with some really great ideas for this project (and maybe some not so good ones, too - sorry, you have to take the bad with the good). But I want to provide you a link so that you can look up some really good help tips from one pond builder called ThePondDigger. I like his videos on youtube and I like his style. he's not the only one out there, of course, but I think he has some valuable tips for people like us so that we can DIY our ponds. Check it out and browse around and see if anything appears that might help you out. Here is the link:
http://www.youtube.com/user/ThePondDigger
Gordy