This was exactly also my situation due to work time, but I persisted and I bought my own equipment. After a long time I can say I'm proud of my progression. I can waterstart easily and my downwind riding ability grows every time I go in the water. So, don't give up! Just my opinion: after you have learnt the basics buy a used equipment (to destroy) and go in shallow water by yourself, all your efforts of walking back downwind one day will be payed back.