Hi Becky,
I'm T1, had it 31 yrs (am 32 now!), have an underactive thyroid, polycystic ovaries, a 3 1/2 yr old & a 5 month old baby - so it can be done!
Each time we tried I felt incredibly frustrated at how long it seemed to take to get ready, medically / HbA1c-wise, but it was worth it! It took us around 2 years each time (luckily we conceive quickly!

), as the only way I could get the results I needed (what with dawn phenomenon etc) was a rather fascist approach to carb counting & testing & 3am boluses! I think my HbA1c at conception was around 6.5% first time, 7% (I think, can't remember the exact number!) second time. They will want you to be on the right dose of thyroxine before hand too, as the first 12 weeks are really important for baby's development - seems sensible to get it all in the best possible way first!
The other thing is make sure you are on 5mg (I think that's the right units!) Folic acid for ideally 3 months or more before conceiving & NOT on simvastatin any time within 3 months - it's nasty stuff & contraindicated with pregnancy!
A t1 pregnancy is really hard work, and can be quite stressful - I certainly felt it was a massive responsibility... but it is SO worth it! Wishing you all the best,
Twitchy x