How to improve swim with small pool - and ocean

I want to improve my Ironman 70.3 time. I only have access to a 14 m pool and the Pacific ocean (back yard - pretty cool). I am fine swimming in a smoother open water but i tend to get pushed around and fight the water when there are alot of currents - while others swim by me like its easy. What kind of training should i do to build up my swim time without access to the usual 50 m endless sets of drills. I have looked at coaching programs but they all expect access to "real pools"
I do not come from a swimming background and am in my 50's