Waterproof material for bag making..

cordura and ripstop polyester will probably be the bulk of what you are looking for if you are making an outdoor bag. neither are actually 100% waterproof, but then no outdoor bags are meant to be. then of course you will probably need velcro, YKK zips and webbing belt material and maybe goretex or similar?
i cannot imagine having any luck sourcing fabrics suitable in ireland. you will probably find most of what you need online though. here are some suggestions.

http://www.fabrics-n-stuff.co.uk/
i have used fabric and stuff once. good service and price. nice people to deal with.

http://www.fashionfabricsclub.com/
dont know anything bout these guys. but they seem to have some ok stuff.

http://www.snydercreek.com/index.htm
i will be getting some of this stuff, but its only camo patterns

http://www.leprevo.co.uk/
these are great guys for leather, of you ever need that kinda stuff.

of course, dont be afraid to search ebay for fabrics
http://shop.ebay.com/merchant/seweasyus_W0QQ_nkwZQQ_armrsZ1QQ_fromZQQ_mdoZ


http://www.backpacking.net/makegear.html

hope some of this helps. if you find other gems, please let us know. good fabric is hard to find.