I was there last year in July. Take a big kite. The flat water in the lagoon at Sanur is awesome to kite on, and if the wind picks up you can head out to the breaks beyond the reef. You can also hire gear on the beach at Sanur.
From what i saw Canggu would be the best bet for both, stayed with a mate who lives there and there are a few cheap places to stay, you are not going in peak times so just rock up at a home stay and there should be a room. Get a scooter for a few days (We hired a car for AUD10 per day) and there are plenty of breaks up and down that stretch of coast.
Had a couple of good surfs at Canggu and there was one day when the wind absolutely ripped in, but I did not have my gear and you cannot hire there, so I had to settle for watching guys rip it up in awesome swell and wind

.
The waves on shore at Kuta/Legian are awful, the ones worth surfing are offshore.