Hi Emily. Funneling means your cervix is slightly open at the top - imagine a plastic funnel that you would use to fill a drink bottle, that's how your cervix is looking. The 23mm is the amount of closed cervix below the funneling. I personally would be asking what they intend to do about this hun. The funneling means that your cervix has begun to chang eunder the weight of your growing baby, and needs close monitoring at least. There is also a chance they could still place a stitch at this stage.
In the meantime, I would rest - complete rest if possible. That can actually change your cervix and it CAN close up again. I have always said that if they scanned every woman's cervix in pregnancy, they'd see many more with changing cervixes who still make it to term. Try not to panic at this stage, but I would definitely be taking the weight off and not over doing things over CHristmas. Good luck hun, thinking of you xxx