Can I use a 3 pin kettle power lead instead of a 2 pin kettle power lead

If your device only has two connectors, it seems to be insulated. Then you don't need a ground connection. If the cable with the three connectors fits into the socket of the 2 pin, I don't see a problem.

These are IEC 60320 standard appliance cables. This standard includes many different shapes for the connecting plugs and sockets, and they have been carefully designed so that unsafe combinations are physically impossible. It is safe to use this "C13" cable (10 amps, grounded, three wires) to power a device with a "C18" socket (10 amps, ungrounded, two pins), and therefore the connector shapes allow you to do so.

(Ironically, one of those impossible combinations is using a C13 cable to power an actual electric kettle; that's considered a high-temperature application and it requires a C15 cable. But you can use a C15 cable on a device designed for C13.)