Yes you can cross borders and normally at no extra charge, please check here:-
To view the CROSS BORDER terms and conditions. At STEP2 of our 3 step online booking process, alongside the car photo of your choice, there is a link entitled “TERMS & CONDITIONS”.
Clicking on this link will open an additional smaller window, with the terms and conditions appertaining to that particular car/supplier. Look under TRAVEL RESTRICTIONS
Try a few different suppliers as each supplier/vehicle type may have a different cross border rule.