To start with, hiring an instrument means you can check that you enjoy playing before you invest in buying one.
This can also give you time to try out instruments.
It's a good idea to try flutes out in person even if you don't buy the instrument from that specific shop.
The Yamaha 212 comes highly recommended. My clarinet and saxophone are both made by Yamaha.
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.