Any Spearo's in?

Been tentatively getting into Spear fishing the past couple of months. Figured I'd better start with swimming and snorkelling first, so I got some cheap additional gear and started getting in the sea. I've been swimming in the local pool twice a week as well.

Then I bought a pole spear and had a few goes with that. Once, I anchored my paddle board and tried spearing from that but viz was rubbish but the general idea had me hooked!

Next time was amazing! Other than the complete lack of fish. Ended up spending 4hrs out there looking for Flatties in the sand and shot a legal limit Gurnard! Which was the only fish I saw 🤣 (My friend eats anything that swims so he took it off me and said it was lovely!).

Next time, I found three legal bass on my way out to my chosen spot but where I was towing my float with the pole spear, the float line caused the pole to stop mid water half way to the fish so they laughed and swam off.

Now I have a Rob Allen Tuna 800 and took it down on Wednesday. I could only get there at low tide so viz was rubbish and there was no Bass this time. But I still had fun practicing firing the gun and getting some muscle memory for resetting the mono.

If I'm honest, my erratic schedule means I'm almost always going to be spearing alone so I'm not going to be keen on stretching myself too far- but I'm wondering what tips folks have used to close the gap between your dry breath hold times and your spear fishing ones?
I got a cheap dive watch and found out I was only diving for a minute at a time (the mark I was fishing was about 6m at low tide) but on the sofa, I can do 2 mins most of the time and my pb is 3m15.

I want to shoot fish, not be a free-diver so I appreciate that at better marks, 60s could be ample (as I'll have plenty of spare capacity for dealing with catching something then) but it would be cool to be able to try an occasional ambush on the bottom.

I'm presuming it's mostly mental and fitness/technique based?
Maybe longer fins will help eventually and I might add one more kg of weight (wearing 6kg at the minute).

One specific problem I have is when breathing-up. I relax, my HR lowers and I get ready to take my final breath... but as I relax, I always seem to get a snorkel full of water and then have to clear and start all over again 🤣 I'm not even sure whether relaxing causes me to let water in around the mouthpiece or if my head drops and it comes in the top but it happens pretty regularly and I wondered if it's a known thing?

Another thing I would be interested to know is what methodology people use to predict Viz at their chosen marks? Being 2h from the coast on a bad day means it's almost impossible to tell. I try and judge from the Boscombe, Bournemouth and Southbourne webcams and go for the second or third day of low swell on a neap tide with winds under 10mph on shore or 15mph Northerlys.

I'm assuming its site specific and always subject to pot luck but would be interested to know any general rules that may help.