Followed advice above booking test after 11.00 pm last night and got a test for 20th January... System was showing next available slot was March. Thanks a mil
Mine was due in the first few days of January, and they sent me a letter with an exemption. I don't have to do it until the 18th of may now. The letter even says my nct is now valid until then.
I didn't ask that letter just arrived in the post mid-December.
The letter said something about the date my car was registered, and that is why I don't have to do it until May. I did the NCT 2 years ago.
They must just be using the date your car was registered as a guide so it's probably pure luck if you get an extension or not.