Is it likely that the trip to EBC will go ahead at that time of year, what are the weather conditions like in November/December?

Yes, the trip ‘ll go ahead during that period. Infact its the best time to trek in Nepal. When the weather remains glorious with bright sunshine and calrity of mountain peaks are conspicious.The days are warm and filled with sunshine, whereas nights are reasonably cold,
During Oct – Dec, the average temperature will be:
Maximum day time temperature approx. – 5 to 12 degree celsuis (41 F)
Minimum night time temp approx. – 7 C (19 F)
Wind Speed approx. 4 kmp ( 6 Mph)
Sunshine hours/day – 7 hrs.
Just for information purpose, one of the Nepal’s prominent festival fall during Novemeber – Diwali.
It portray Nepal in colourful light. It can potentially add a new dimension to your experience.