Do you mean July 2012? After being out of work for 6 months, I imagine that just basic fitness will be the first requirement. I would think that you both could get quite fit between now and then, but I would take care not to over-train as you would not have much time to recover should some injury, lameness or pain issue arise.
I would first start with free choice hay and a ration balancer or a simple feed like strategy, etc. Then a couple-three mile walk/trot trail ride or two to see where we are in terms of fitness (how does the horse do, what sort of recovery does he have, etc) right now, and then work from there. Another member here passed this link to me: Endurance Riding
I think it has a good overview and general plan.
Then, once you have that info, you may be able to develop a more specific training plan. Remember, while a horse's muscle and cardiovascular fitness (wind) can increase considerably over as short as 6 weeks, it takes far longer, on the order of 12 weeks, for the bones, cartilage and ligament to catch up, so you must be very careful not to cause overuse or strain injury in the mean time.