I expect they will offer around £7500 initially , what it costs to replace doesn't always come into it . Who is your insurance company ? This will make a great difference to what you get offered and also depends on how quickly you want the cash . Do a Webuyanycar quote too , it will give you some idea .
What you get for it is more down to luck . You will not be impressed with the manner in which it happens and i would estimate you might get a max of £8900 but nearer £8.5k . Good Luck
I dealt with a man about ten years ago after a serious accident , he had crashed his BMW ten days after paying £23500 for it from a BMW Main Dealer , his insurance comapny eventually paid him £19000