Welcome to the best computer golf game. As for free credits I personally do surveys and video views and I did these for a year accunulating credits. I used the starters clubs in that year and with hindsight wish I upgraded much earlier! As you say, the starters clubs are not much chop, but you can still score well with practice on the easier courses and from tees Tour Pro and under.
However as this has been the season of goodwill, you now have two new Ping wedges which should help your game. All you need to do is equip your bag and practice, and practice, then practice a lot more!
Most importantly have fun.
Alan