Congratulations NoName! Yip the first trimester does feel like it goes pretty slow, but soon you will be out of there and into the 2nd!
Not too sure about the custard but yip you can have cream as long as its fresh (i think they say consume within 2 days of opening...maybe) You will be able to find info on food from here
linky dinky
With the dentist make sure you tell them that you are pregnant. They can't do exrays on you, and i spose they will help you with info on wether you can have the anethestic. i have a feeling they usally say wait until the 2nd trimester unless its majorly urgent.