Rest assure that your SIM will be very much be active till 11 January. I'd like to inform that if not use the SIM or top up the SIM for more than 6 months then the SIM is deactivated. You can check more info how to keep the SIM active from the link: https://giffgaff.com/boiler-plate/terms#Cancellation
Sim won't be getting de-activating in two months. Please go through the steps below to keep your SIM active:
> At least three calls, SMS or MMS made to another number (For technical reasons, this does not include emergency calls (i.e. 999/112) and SMSs or calls to giffgaff services (i.e. 2020, 43430), > At least one connection to Internet, > At least 4 received calls of more than 10 seconds, > The receipt of Payback points (for recruiting new members or participating to the Community).
These criteria are required to perform once in a six months to prevent your account active.