By Diliff (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
Europe and Asia. The western race breeds in Iceland, northern and central Europe and winters in Scotland southwards to northern Africa and eastwards as far as Iran. The eastern race from which the domesticated types are believe to be descended breed from Turkey and Romania eastwards to eastern China and winters from Asia Minor eastwards to south-eastern China.
Wild birds from Iceland winter in eastern and central Scotland whilst feral birds descended from reintroductions by BASC (formerly WAGBI) occur in river valleys, gravel pits and lakes in country parks etc. Until the nineteenth century, Greylag Geese used to breed throughout Scotland and in parts of England and Wales as far south as the fenlands of East Anglia and the reintroductions were intended to restore this historic situation as well as provide sport.
Domesticated forms differ considerably from the wild form and feral birds will hybridise with other species in particular, Canada Geese, which are often present at the same locations. Some of the different forms are illustrated below:
By Bjoertvedt (Own work) [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons
By Kenneth Darland (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
This work has been released into the public domain by its author, Redleg at English Wikipedia.
By Davee [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
By Joe Thomissen (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
In reality of course, it will probably be much easier to take a trip to a local country park if there is some water present as this is a ubiquitous feral bird.
Myrfyn Owen & D. G. Salmon (1988) Feral Greylag Geese Anser anser in Britain. and Ireland, 1960–86, Bird Study, 35:1, 37-45, DOI: 10.1080/00063658809476978
Janet Kear (1990) Man and Wildfowl, T& AD Poyser