I hate to say 1 weekend day a month will not allow sensible progress to be made. However with effort fast progress is possible. I have recently watched someone at my local club start from scratch, achieve his first solo within 3 months and then complete bronze and cross country endorsement, fly a K8 100km land tour the vintage gliding museum at Lasham, take a low aerotow and fly 100km home (in the K8), complete a first 300km flight and then 420km of a 500km attempt. Ab-initio to 420km in 11 months. Granted it has been a superb summer, but still not bad for someone in full time employment.