KAT I sort of sit in the same boat as you I am naturally skinny,and go to gym for some mass and shape.. Eating 5 meals a day is impossible, I am lucky to get two decent feeds a day. I do try to eat as much as possile when given the chance, but time restraints for lunch breaks and shift work stuffs it all. You also need to watch how much fatty stuff you get, when pigging out so to speak, it could all go badly rather fast...
I have a shake before gym, and any time i feel I need to top up as I haven't eaten properly, having a good meal is allways best and what I would like to do.
I notice if i haven't eaten well for a day I will wake up feeling very hungry, but cant eat much as it makes me feel sick, so I have a cuppa, and then breakfast 30mins later.. having a decent breaky really kicks off the day well, get creative with eggs, they are usually pretty quick to prepare. , my favorite is a chicken fratata..
Just try to graze all day. if you hav eto go teh shake option more than twice really value add to it, most things can really effect the taste so experimenting is essential, planty of good ideas in the nutrition area, Current favorite is 500ml milk, 2 scoops protein ~ 45g, banana, and frozen berries, simple quick if its hot and for after gym, for a better carbo hit i add ice cream. the berries really take the edge off the banana
As for training in the evening i read something and I tend to agree personally, hitting the gym in the morning will help burn more calories, as the body is starved from the long fast overnight, gym in the evening you will find you are much stronger, unles you have a manual lifting type of job. heavier weights means better lifts = bigger. gives you way more time to get the food perfectaly timed for a good workout..