The Art Director of Pokémon Sword & Shield has confirmed that the Galar region is based on the UK and that he was asked to help design it due to being British himself.
The regions in the Pokémon video games are based on real-life locations. The Kanto, Johto, Hoenn, and Sinnoh regions are all based on parts of Japan, Unova is based on New York and the surrounding areas, Kalos is based on Paris, and Alola is based on Hawaii. The fans have speculated that the Galar region in Pokémon Sword & Shield is based on the UK, especially as the map looks like a flipped version of the British Isles, with Scotland in the south and England in the north.
The inspiration for the Galar region has been confirmed by James Turner, who is the Art Director on Pokémon Sword & Shield. Turner was interviewed by Game Informer and he confirmed that the Galar region is based on the UK and that one of the reasons that he was brought onto the project was due to the fact that he comes from England and is familiar with its countryside.
Turner discussed his reasonings for the design choices of the Galar region and explained that British people have a native negativity in regards to the beauty of their country and that they don't always appreciate the wonders of their homeland. The fact that Game Freak had a British Art Director on the project has allowed for a native perspective of the country that can be reflected in the Pokémon world in a way that is genuine, in the same way that the first four regions were so steeped in Japanese culture and mythology.
Turner has worked as an Art Director or Character Designer on several Game Freak titles, including Pokémon Black & White, Pokémon X & Y, and Pokémon Sun & Moon. The Pokémon designs that were created by Turner include the Vanilite line, the Golett line, the Vullaby line, and Guzzlord.
Pokémon Sword & Shield will be released for the Nintendo Switch on November 15, 2019.
Source: Game Informer/YouTube