If you succeed in doing 2 hours a week then you should be able to complete a PPL in around 6 months however: there is a high probability that you will loose 50% of your booked slots due to weather. They won't be evenly spread so some flexibility is required to average two flights per week. There are points where it might pay to concentrate the flying a little, just prior to solo and when completing the navigation exercises. Starting this time of year a good target is to complete by September.