AirhostessMum - at my name :) oh yes, I was only 9 when I started 
29 is not too old! A friend of mine has just started flying at 50+!
If it really appeals to you, just start applying and see if you can get a temporary summer season with a charter airline first. Honestly, age is no barrier. Personality is everything when it comes to being crew. They are looking for someone who loves being with people, who's adaptable, friendly and approachable - someone who obviously wants to do it, and can deal with all the passengers that givemushypeasachance refers to with a smile on their face at two o'clock in the morning after a 6 hour delay.
If you're not fussed about being on long haul, and just want to fly, then maybe one of the low cost airlines would suit you better - home most nights depending on your base. Charter = lots of night flights, but if you've got kids, you'll be used to being up all night anyway! Are you near big airport (better choice to apply to)?
Those courses are ok (I used to teach a cabin crew module at a local college) but they don't guarantee you a job - I'm not sure whether the airlines set much store by them, it's more what they see at the interview stage that determines whether you're in or out.
And yes, I'm thinking of applying again next summer - miss it loads. :(
Hope this helps - go on, apply! PM me if I can help with anything else.