Yep, it's hard.
After 4 lessons you can expect to just be finding your way. Whilst you are bound to have some reasonable understanding of the environment and a capacity for situational awareness, the "stick and rudder" skills will be totally new for you, and you are also finding your way into a captaincy role that won't have been part of your back seat experience.
Plus, it's a sad fact of life that none of us are as young as we were, and when you went through your navy courses you were a lot younger with a youngesters capacity to learn fast.
Best advice I can offer is just don't think in these terms - enjoy the learning process, and work as hard as you need to, but again just treat that as part of the fun. When you get there, you'll get there. Worrying about progress is actually likely to slow you down.
Your prior experience may help you a bit, but not that much so don't expect to be much, if any, faster than any other student in reaching your PPL. Once you have it, then your navy experience is more likely to start being useful as you get into management of the aircraft, planning real flights, and so-on.
And absolutely nobody cracks landings in the first 4 hours. 10-15 to do a consistently survivable landing without your instructor having to intervene is more realistic.
G