I never bothered with this LTG thing as it was so far out of my reach I simply dismissed it (I only really started flying BA at all in 2013, and didn't get to gold until 2014). However, I have just looked and realised I too have just crossed 20k TPs.
So whilst GfL appeared out of reach in a reasonable time frame previously (and by reasonable I mean 'within a time frame that it won't be enhanced away'), I could feasibly hit GfL in 3 years or so if I stop flying other carriers once I hit the 3.5k TPs, as I do currently.
Something to consider, I guess.