Hi. I think you are doing a great job getting your body ready for pregnancy and getting rid of hormones that cause insulin resistance (ironically mimmicking the later stages of pregnancy!).
I assure you are in the UK and being treated at a clinic by a diabetes/gynae clinic? (or will be when the time comes).
I have had 3 kids whilst being type 1 and the frequency of visits and monitoring will increase towards the end of your pregnancy and according to what if any difficulties arise. For example I was seeing someone monthly but then my visits were weekly and at 34 weeks I got clamped to a hospital bed with pre eclampsia. For the subsequent pregnancies I then took each day./week as it came because things can and do turn out differently for each one!
For example its not automatic that you will get bad hypos at first though if you do feel sick (again not everyone does) and are being super careful with blood sugar control in the critical first 12 weeks, then you may find you tend towards more. Equally you may need more insulin at the final stages because of the insulin resisting hormones but I've seen plenty of posts from wonen who don't! At least with Dexcom you will be able to react quickly.
Food
You should be taking prescribed folic acid prior to pregnancy (not the otc stuff) and I would eat whatever I normally eat to keep my blood sugars in range ensuring plenty of good fats, leafy greens, dairy and protein to build a healthy baby. Its been 11 years since my last pregnancy but I never worried about sushi, soft cheese and I didn't feel like alcohol so I am not sure about the current advice but I always think its amazing how all those French women eat plenty of soft cheese (gut friendly bacteria!) , drink wine and still produce healthy babies...
I am sure someone who has done this more recently will be along soon but my best advice would be to try and enjoy the pregnancy in spite of all the medical attention you'll get and the anxiety you may then feel. It is an amazing time!