Fabric? I'd advise Fire retardant Calico if you're making a large wall hanging, can never be too safety concious! You can buy it by the metre on eBay.

Hi - you can have them custom made - so have a look at these sites :)

http://www.quotethewalls.com/

http://www.wallquotes.com/

http://vinylwallexpressions.com/

http://www.ebay.co.uk/itm/YOUR-OWN-CUSTO...

https://www.etsy.com/uk/shop/luxeloft

Loads of choices there to get your own quote designed - good luck :)