I know it varies etc but roughly how much would it for cost 2 adults to go on holiday from england to perth australia for a week? also if you have some suggestions on places to stay and prices, or a site would be better, this would be great thanks in advance
Shop around for fares with different airlines the prices vary . Ask at travel agents and also look on the net. once you are here look at www.wotif.com.au /perth for last minute hotel deals. the pound is very weak against the Australian dollar at the moment so you will find things expensive here now . It's about 60 pence to the dollar and it wasn't long ago thet it was in the range of 30 something pence
I hope that you plan to go somewhere else as well as Perth as a week in Perth on its own would be pointless not to mention you will take at least 24 hours to get there. A holiday in Australia needs to be at least 3 weeks!
You would have to go via Singapore or Sydney anyway.
Emirates are doing cheap return flights just now. Adult returns are under £700!
You will defineatly need more time than a week though 
A WEEK! ! ! Your jet lagged for 3 days pending flight ! ! !
How much would a holiday cost from england to perth australia?