Just wanted a hand setting myself some goals for this year and was hoping someone could help. I know riding/training is a lot more enjoyable when there is a clear goal in mind at the end so i want to set myself a realistic target now to accomplish sometime in july/august.

At the moment i ride exclusively on the road on a road bike. I'm 17 at the moment and i only get to ride on weekends right now as it's dark but i usually do about 30-40 miles on saturday then a slower 10 mile ride on sunday. To give you some idea of my fitness (or lack of) i can ride 20 miles in 1 hour and 30 in 2. Eventually i would like to do a ride like Lands End (South England) to John O' Groats (Top of Scotland) which is a 1000 mile ride so i want my targets to be in endurance, however 50miles is the most i have ridden in a day and took about 3 hours combined with a large break. By about March i will have sat and sun free for training and about 2 hours a weeknight. So what would be a realistic goal to set myself to accomplish?