It would depend upon the mpg of your car (and your driving style).
As a guide, however, I'd estimate about �85 in my elderly 1.8 litre petrol-engined Mondeo estate. (That's based upon getting about 7 miles out of every �1 of petrol that I put into it).
The BBC quoted the average UK price of petrol, during last week, as 113p per litre. That equates to �5.14 per gallon. If your car does 30mpg, you'll use 20 gallons, costing about �103. If your car does 40mpg, you'll use 15 gallons, costing about �77. If you've got a small-engined car, you might get 45mpg out of it, which will cost you about �69 in fuel.