That's my recommendation If you were to buy clubs now, yes you should see an improvement in your scores, but the downside is you will outgrow the clubs when you get to the next Tier and therefore wasted a lot of credits. If you can wait till level 59, the G20s can take you all the way to legend. It may seem a long way away. The Raptures are level 48 but these will not take you as far as they are not high trajectory clubs like theG20s.
If it was me, 3 wedges that will fit in with your desired Irons (work your way back to have evenly spaced clubs) and then a putter. These are the clubs that help you score well.
Obviously if you have credits/cash to burn yes by all means upgrade and again depends on the meter speed you can handle, but the R11s are good but will take you no further than Master.
Personally I would take your time, level up and learn the game, in particular the short game. try all sorts of shots and see how they work. Obviously the starters clubs will not allow much, if any spin - this is where the wedges are worth their weight in gold and a cheap way to improve.
Hope it helps.