Hi, I do quite a lot of hillwalking
1st I would highly recommend you wear your boots as much as poss before the walk to break them in... the last thing you want are blisters on your walk!....Also take some compeed blister patches with you. they're the best thing out there!
Foodwise.... bananas, peanutbutter & jam sandwiches, and nuts/trail mix (stashed in a pocket) are my faves as they are slow release energy foods. Jelly babies stashed in a pocket are also good for a quick energy boost!.... and way cheaper (and tastier) than the posh energy bars!
This time of yr I'd prob only take a litre of water/juice..... or 500ml and a flask of coffee
Take some waterproof trousers aswell as a jacket just incase, and layering is the best way forward instead of having say a thick hoody, go for 3 lightweght tops like a t-shirt (I would normally recommend a fast wicking or thermal top but if you're not doing much walking after this then it'd be a waste of money, a t shirt will be fine
) a long sleeved top and a fleece (or 2 thin fleeces) that way you have the option to add or take off as you please and they don't take up as much space in your bag. I would not wear jean... a couple of pairs of leggings, track bottoms, combats are all good. Specialist walking trousers can be v expensive!
Pace wise, I wouldn't worry too much... you'll soon fall in to a rhythm but as a rule of thumb, the average time to walk a km is app 20mins, with a pack x
Goodluck.... and have lots of fun
... Where are you going to/from?