Been told switch is in a cooker zone and Napit code it as C2.
Have you had the EICR yet, or was this from another source?
Napit don't code anything - though they produce a book "Codebreakers" that gives example codes for various situations. The inspector makes a judgement on the day based on a variety of factors, so it's not just a simple 'tick box' exercise, or rather shouldn't be. Any code, but in particular C2s or C1s should be backed up with a regulation number that has been breached.
Unfortunately, The Codebreakers book seems to differ in some areas from other guidance available from people like Electrical Safety First.
Their Best Practise Guide states that a C2 is appropriate for
"Fixed equipment does not have a means of switching off for mechanical maintenance, where such maintenance involves a risk of burns, or injury from mechanical movement",
But in this case there is a means of switching off. Does the same switch also isolate the oven?
The socket is potentially an issue but personally the only way I could see it being a C2 is if that was the only socket in the kitchen so was likely to be used for trailing leads. I assume that's not the case?