What electronic device should I get and where should I get it?

I am a teenager living in the UK and I want to buy an electronic device to do this on:

Browse the internet.
Stream music.
Use Deezer (deezer.com).
Check emails.
Manage files.
Shop online.

I want to do this for as cheap as possible, so what should I get and where should I get it?

Also, I don’t mind people outside of the UK answering this, but they probably won’t know where to buy it from in the UK. Any help is greatly appreciated though!