Re: the amp, if you’re looking at around £500, then Yamaha or Onkyo are your real choices. Both keep swapping best buy between them in the reviews. A mate has a Yamaha from several years ago, but it was going to be the Onkyo. Both have a number of HDMI inputs, which give upscaling, not that you’re likely to need it with a Bluray. I think you’ll need decent speakers, the KEF satellite/sub combo is superb. It’s not worth skimping on a system, they last for years, you want it to be pretty future-proof, so as many HDMI and optical inputs as you can get, really. Huge amounts of power are irrelevant, unless you live in a really big detached house!
My own amp is a Yamaha, about eight or nine years old, just prior to HDMI, and I could really use several, but I use optical from my DVD, and a Minidisc, as well as my Mac Mini.