Toyota Repair: RAV4 speedometer problem, vehicle speed sensor, automatic transaxle

Question
The speedometer on my 2003, 38,000 mile RAV4 has suddenly failed.  As I live in a remote area of Scotland, with the nearest dealership a considerable distance away, I'm unable to obtain an immediate repair.  The question is then, is there a serious underlying problem that would prevent me from driving the car for a short while, before I can effect a repair? (Apart of course from the obvious legality of such an action!)

Answer
In most cases this is due to a failed vehicle speed sensor mounted in the transmission, I'm assuming it's an automatic transaxle, although the computer does need to see a speed sensor signal input the car is driveable but the check engine light may turn on and there may be a noticeable driveability issue such as erratic shifting and loss of performance.