Hi Laura,
I'm A T1 30+ yrs and i don't know really if your dry mouth is down to your diabetes alone. Thirst is usually because of high sugar levels, as i expect you know, but that thirst feels like it comes from your belly (sounds weird but if you've ever suffered a big high you'll know what i mean!).
The reason i'm replying to you is that if your dry mouth is also sore or feels rough it could possibly be oral thrush, which is something diabetics, especially women, are prone to. It sometimes gives you a white-ish coating on your tongue, but not always. Good news is treatment is quick and easy, but you'll need to get a diagnosis from the doc.
It's only a suggestion though, and if i think of anything else i'll come back n give you a shout/
Anni x