going on holiday when 14 weeks pregnant

We're going on holiday for a week to a city destination. This was booked way before I knew I would be pregnant. 
ATM, I feel like utter crap! Constantly dizzy, feeling sick, being sick and super tired. 
It's going to be a lot of walking, I'm scared of what I'm going to eat because ATM I live on pasta 😂. I don't want to ruin this holiday but I am dreading going :(
Anyone got any tips? 
Luckily the flight is only 3 hours long..