Hi
@louiseB6 and welcome to the forums.
There've been quite a few threads on here from people with high preconception hba1cs,
While 66 isn't great it could be a
lot worse.
And remember that in the olden days pre glucometer (eg my T1 mum) hba1cs were much higher than they are now. (My T1 mother in the early 1960s went up from Hampshire to a London teaching hospital to have her antenatal care.)
The good news is that glucose sensors allow for much better diabetic control and scans allow doctors to detect any issues at an early stage. Statistically, higher hba1cs lead to a greater likelihood of issues, but it's a numbers game and modern T1 mums are in a better place than ever before to have successful pregnancies.
So good luck, and if you're pregnant now, congratulations, and get yourself to a doctor asap so you can reduce your bg levels even further and get the antenatal care you need (folic acid etc).