Hi Geoff, Christian here (your instructor

)
Glad to hear you're motivated to carry on with the sport.
As Expatruds mentions, some students need more time than others to learn. This is the case for you and also was the case for me (took me many months of flying before I was comfortable with the kite).
As I highlighted in your written progression/feed-back sheet (just pulled it out and read it again), you unfortunately still have some dangerous habits of grabbing the bar very firmly and pulling it in all the way, along with a wide grip. This combination of habits is what makes kiting more dangerous for you, especially when flying larger kites on the beach, especially on windier days. You are MUCH safer
in the water and for those reasons you should avoid flying on the beach as much as possible.
Unlike most students in other schools you are perfectly capable of performing deep water self-rescues without any assistance, you've done 4 of them (all successful) during your lessons. Hence, you should have nothing to worry about going out for a body drag in deep water. In fact that's the best thing you can do to improve and build confidence and flying skills. Just stay away from waves/shore breaks and over crowded areas.
I see you have lost your board in a different thread, sorry to hear that. Remember that after your 3x2hours lessons, you were still having difficulty with upwind body drag and kite control... and we weren't ready to bring the board to your hands or in the water just yet.... As a result I recommended you book more lessons and was hesitant about recommending you to go out on your own... but I totally understand you would go out by yourself after spending on gear. I would've done the same thing and actually have done the same mistake myself. Went through many kite mares myself until I just accepted I needed more lessons...
Finding a shallow water location may help you to build confidence, but remember each locations has it's pros and con's. Melville has a very narrow beach and lots of obstacles nearby, kites end up in trees regularly there. Winds can get very gusty and it can get very crowded. Point Walter would only work on Easterly winds, which are extremely gusty and also almost on-shore on the upwind side of the sand bar or off-shore on the downwind side. I wouldn't recommend this place for any beginners.
As Andy T suggests, you definitely should avoid self-launching, especially at your level. Contrary to what Andy T says, Self-landing is fine
as long as you release your safety system first, which is something you've done well a few times by yourself during the lessons.
For your own safety and ease of progression I would strongly recommend budgeting another few more lessons (with practice in between) until you get more comfortable, confident and safe. It's not rare that our students book more than 3 lessons, nothing to be ashamed of.
Christian