I really like Yamaha as a brand overall and I have several Yamaha instruments.
The Yamaha 212 comes highly recommended. Some other brands require a bit of set up in comparison to Yamaha which are known to be good straight from the box.
The Yamaha 211 is very similar, just older.
Claire Bownds sometimes has second hand instruments to sell over in Witney.
I bought my instruments from Dawkes and some from eBay.
If you can, it's a good idea to try flutes out in person even if you don't buy the instrument from that specific shop.