Hey thOmO, welcome to Seabreeze !!
If you want to mainly SUP for surf then just get out there is my advice because Paddling in the surf is always going to be harder than the flat water.
Even paddling technique differs from flat and smooth to the surf and then again for ocean racing IMO.The ultimate for a beginner would be to have a warm up paddle on the flat water then head out into the waves after that , but that depends on where you surf and paddle, estuaries are great for this.
If not then use the flat water for practicing balance and your turns (kick turns) dont put them off, practice right from the word go because in the surf they are important for quick turns to catch waves that pop up fast .
Just get out there fall off heaps have a laugh,as we all did this! and most of all enjoy being a begginer again and the challenge that lies ahead

Tip, If there are any seasoned paddlers in your area watch how they use the paddle. ie; top arm,length of stroke,body movement,etc or go on utube and find some good footage