dream pc build for £3000 / $3500ish

hi all,

So with a mega amount of saving i have about £2500 - £3000 to get a new pc. but i need help on what is compatible with what and whats more likely to last slight abuse/ over use. I want it to be as future prof as possible and pretty hardy as i am known to play for 8 hours straight hehe. the other problem i have is due to a health condition my flat has to be warm usually about 21 -23 degrees C. I would appreciate any hints, tips and builds you could suggest.

thanks :)

So here's the GA, Thanks for the help :)
GA 1