correct SUKRW, theres also normally a 2 or 3 month deposit required at the beginning, so:-
(3 x £450) + (35 x £450) = £17100.
Although you do normally get your car tax paid for by the lease firm for the duration of the lease, so that saved you around £650 in total. And some deals include all the servicing, tyres, insurance etc, but these are normally priced accordingly.
And then at the end if you have exceeded the allotted total mileage theres also an excess mileage charge to pay of aorund 6p per mile, and then the potential for being charged for any dents/scratches on the car.