Sorry Lisa, I have no idea what the Syn value would be, but I didn't want to read and run.
Hopefully someone on the forum will be able to help, and give you a rough idea.
Try not to worry though, we all have little blips like this. The main thing is that you enjoyed it, and are ready to get straight back on plan. Afterall, it's just 1 meal out of 21, and is unlikely to effect your weight loss a great deal.
Good luck xx