My 58 plate Octavia's battery went almost flat a couple of times in the last few weeks and I became concerned that I don't have the code for the radio.

How do I go about finding out what it should be in case I have to replace the Battery?

It the radio was OEM to the car then AFAIK you shouldn't ever need a code. 

Assuming it is the factory fitted radio, then you don't need it. The code is stored on the dash panel and is compared with the radio when you power it up again. Just a few seconds delay before coming on again.

 

Edit  We both posted at the same time.

Edited 23 October, 20178 yr by pikpilot

Think up to three can be stored. Swapped over my Audience for a Bolero and never needed to reenter the code after the first time. Disconnected the battery many times.

Your car is coded to the system. as long as you don't remove/replace your radio then it's fine.

 

Even if you remove it, it should maintain up to three codes in the memory.