I've just completed a p/t gdl 10 years after a non-law degree. I'm 32. The gdl was academically tough (and I have an oxbridge background) but quite well spread out over the 2 years. Essentially I did 1 day in college every 3 weeks. I worked 3 days a week and have 2 kids and it was manageable. Obvs don't know first hand how it differs from a law degree but get the impression the gdl is more vocational.
Am now doing a f/t lpc and it's rather nightmareish!