hello michael, there are two ways to get your hanggliding licence
1. hard yaka bust your guts kind of training, where you do all your training on the hills and the hardest part is carrying the glider uphill on your shoulders after the glide. takes few (3-4 if u lucky)months to get your licence. training schools generally run by solo operators.
2. easy and slightly expensive way, here you go straight to 3000ft in tandem flight with instructor towed by trike and then glide down learning controls and landing procedures. the training also involves winch towing for solo training flights. also involves some hill training as well. you get your licence in 2 weeks training(if weather is good). training facilities generally run by well equiped schools (airfield, trikes for towing, winch tows, multiple instructors, sometimes access to subsidised accomodation etc.)
I dont think age 55 is any problem especially for method 2 . however if you are concerned you can always go for paragliding which is basically same as hanggliding only less hassles (less setup and packup times and are able to utilise even marginal lift to stay aloft) it only takes about 2-3 days training before you will be riding high(under supervision )
hanggliding costs: training around $2000
good used beginer glider+harness around $2000-$3000
what you get: ultimate adventure weather permitting
my 2 Cents