Full fat butter for the calories.
Wholemeal bread may be too high in fibre. But unless you are feeding a lot of other high fibre foods a bit of toast in the morning is not going to cause harm.
Krissy, salt in homemade bread is to stop yeast action so your bread doesn't over rise and go all floamfy, does it still turn out the same as if you use salt? I've never done it without.
ETA
Low-fat, low-calorie and high-fibre
It isnt advisable to give low-fat, low-calorie or high-fibre foods to babies (also see the advice in Drinks). Babies have small tummies, but are growing fast. They need foods that provide lots of calories and nutrients in a small amount of food, rather than bulky high-fibre foods.
Fat gives them energy and provides some vitamins that are only found in fat. So choose full-fat dairy foods.
Dont give your baby high-fibre versions of foods, especially those with added bran. It stops babies from absorbing important minerals such as calcium and iron. Its better not to give your baby brown rice, wholemeal pasta or bran-enriched breakfast cereals until they are older, although you can give some brown bread.
from here https://www.eatwell.gov.uk/agesandstages/baby/weaning/