Yea - don't mix speaker brands.
Setting up is quite easy, if you can't ask your dealer just post any questions on this forum, but it is quite straight-forward.
If you were going to take your time putting a system together, I would advise you get a bluray player, amp and front L/R and centre speakers first, then the sub, then the rears. It's the centre speaker that does most of the work (voices).
My ratio was 33%/66% so pretty similar to bigboss.
You don't need to spend a lot on a bluray, I've just bought a Sony BDPS4100 for my Dad (£69) - a lovely little machine.
I don't know much about the Yamaha HRT3065.
If you really want to put something together quickly, then the Yamaha plus the Wharfedale DX1 HCP 5.1 plus bluray and cables will come in under £700.
However, Superfi for example are doing a bundle with the Yamaha RXV675 and Wharfedale package for £649 - you get a lot more for your money with the RXV675. You will definately save money buying a bundle, and there's plenty of deals out there at present.
But, it all depends on whether you want it all now for £700 or you are prepared to be patient. I spent a few months deciding what to do. I remember I could have gone with a Sony AVR and Q Accoustics 5.1 set up which I could have purchased quite quickly, or go 'up the chain a little' and take time to put together a more expensive system. I went for the latter and it took me 18 months but I am glad I did. I think otherwise I would now be wanting to upgrade.
If it was me, I would be looking to purchase one of the network enabled AVR's that were £500 last year and are now being offered around £350 or less - such as the Yamaha RXV675, and deciding on a £600 - £1000 5.1 setup to pair with it, and just buy the front speakers to start, and as you get the funds, add the rest.