Check your local community center.
http://vancouver.ca/parks/cc/britann...0Workshops.pdf
There is usually shit like that posted on the community boards ..
Probably easiest way is to ask one of the front desk workers and see if there are any upcoming sessions.
(If u know how to swim and wouldnt mind improving it! why not take one of the umm.. bronze cross or w/e.. I dont exactly remember which one but swimming courses include first aid.. not sure which level but i got all 3 from my past swimming courses.)