The vast majority of this forum's users are in the U.S. We're not familiar with your local bike retail market.

There are huge U.K. on-line retailers with a worldwide presence. Some of them have local brick and mortar retail locations. One is Evans Cycles. I see on their web site that they have a store front in York. Why not start there? They know their business and serve a wide range of riding needs. I'd bet that they could outfit you at your budget point. Buy the best bike that you can afford.