I have decided to learn to swim this january, @ 37 it is fair to say I am a late starter. My background is competitive cycling and running.My question is, am I being naive thing I could complete a 70.3 by June/July?
It is very possible to complete a 70.3 triathlon in June/July given that you are unable to swim at present, but it all depends on how you approach learning to swim given your short time scale to be able to swim 1900 metres for the event.
Swimming is the most technical of the 3 Triathlon disciplines so it is important that you have some coaching from a qualified Triathlon swim coach, this could be a tri club swim coach session or one to one coaching. You could try teaching yourself to swim as many people have done but it is very difficult to self pinpoint any technique errors that you could be making which could result in you splashing about in the swim getting nowhere fast and wasting energy.
It might be worth considering joining your local tri club for race info and support as well as qualified swim coaching.
If you wanted a personal swim coach you only need to google to find someone suitable but again contacting your local tri club someone should be able to recommend a suitable tri swim coach.
Good luck with your training and hope you make the 70.3 start line.