Evening Davkt
Im not that clued up on the ATPL side of things, i suppose it depends on what route you want to go down.
You could go the whole hog and put a large financial and time investment into a heavy commercial career, maybe some more experianced posters may point you in the right direction for that advice.
I know a few people who came out of long service jobs at 40-50 and went into aviation, two flight instructors at our club for example.
I sometimes think that at 29, i'm too old to be running down the commercial route, especially when you see these young lads/lasses driving the big stuff!!!
If you fancy it, go for it!