watery foods - fruits and veg among the best
melon
grapes
Satsuma
peach / chopped banana
pear/apples / the berries are full of great stuff - blueberries
mix with greek/natural yogurt, honey or maple syrup...sprinkle with raisins/sultanas/cinnamon/brown sugar and handful muesli or sultana bran or granola
lettuce / spinach /cucumber / tomato /broccoli
celery - with peanut butter in if you can manage, dotted with raisins too if you can ''ants on a log''
pineapple
tinned fruit - the fruit salad stuff is fun - drink all of the liquid
add dips/spreads onto things for higher calories
eg - cottage cheese/ peanut butter
chocolate spread
jam marmalade
wholemeal bread toast ryvita cheese biscuits - the nibble-a-bles
frozen - make icecubes of whatever you like - lemonade, pieces of lemon orange juice, blackcurrant juice
energy foods -
eat jelly cubes, cereal bars, dialoryte lucozade chocolate, Kendal mint cake
fizzies - sparkling or flat, try room temp or icy cold, with a straw, tonic water is my secret hero so crisp and zappy, bottle fizzy water - mix with posh squashand a slice of orange - you deserve a mocktail!!
peruse the non alcoholic posh drinks - eg grape juice fizzy water with fruit flavours..whatever floats your boat
remember dandelion and burdock? 
nibble cookies... get posh nice ham for sandwiches with lovely ''artisan'' poncey name
bread..alather on full fat coleslaw, eat with potato salad
smoothies/milkshakes - whizz up your favourite fruit with massive chunk posh icecream, slurp milk, drink with straw in little sips