Improving speed over distance

Kinda vague title for a training section post I know. I've been upping the mileage on my cycles recently to try build up my endurance. My first long (to me anyway) cycle was two weeks ago when I done 55 miles, partly because I got lost and by the time I came across some road signs I was further away from home than I had planned. Upped the distance to 75 miles yesterday and it took me 4 hrs 55 mins. Granted it was a pretty windy and was riding on a coast road, but obviously I want to improve my times. Was feeling it on the last twenty or so miles and by the time I got home I just wanted to eat everything I could get my hands on. I'm hoping to enter my first event this Summer, the Sky Hibernia Etape (West coast of Ireland) which is just on my doorstep. Just wondering if any of ye wise old sages could advise me on a couple of things.

(i) I'm guessing doing high mileage rides need to be broken up with some shorted faster rides too. If so can anyone recommend some different training I can do on alternate weekends to break up the longer rides and ultimately help improve times (not asking for programmes or anything just suggestions)

(ii) What type of eating should I be doing before longer rides. I usually have a bowl of porridge and some wholemeal bread and bring a few fig rolls to have on the way. Should I be eating more before the ride, was absolutely ravenous when I got home yesterday.

That's about it I think. If anyone could make suggestions on how to make these rides less painful and improve my times I would be eternally grateful. Also If anyone has suggestions on books, or links to training tips feel free to enlighten me.