Use {{location|GB}} to tag expeditions that took place in the United Kingdom of Great Britain and Northern Ireland. It will add Category:Meetup in the United Kingdom to the expedition.
Using ISO 3166-2:GB abbreviations, you may also tag the constituent country/province or even a further subdivision that the expedition took place in. Those subdivisions can be council areas, districts, a London borough, a metropolitan district, a county, a unitary authority or the City of London. Wales and some of its unitary authorities have alternative abbreviations, which may also be used. In Northern Ireland, use Chapman-coded counties, since those are mapped on OpenStreetMap while the ISO subdivisions of Northern Ireland are not.
If the category link appears red, do not worry and create the category. Make sure that it is included in the appropriate parent category, for instance, Category:Meetup in Norfolk is a subcategory of Category:Meetup in England, which is a subcategory of Category:Meetup in the United Kingdom. The subcategories should be sorted in by their respective code.
Examples
{{location|GB}}: the United Kingdom{{location|GB|ENG}}: England{{location|GB|ENG|NFK}}: Norfolk{{location|GB|NIR}}: Northern Ireland{{location|GB|SCT}}: Scotland{{location|GB|WLS}}: Wales{{location|GB|CYM}}: Wales{{location|GB|WLS|BGE}}: Pen-y-bont ar Ogwr{{location|GB|WLS|POG}}: Pen-y-bont ar Ogwr{{location|GB|CYM|BGE}}: Pen-y-bont ar Ogwr{{location|GB|CYM|POG}}: Pen-y-bont ar Ogwr
