Please I need some tips / advice regarding my sunglasses fogging up in the surf, I have to stop and sit down and rinse my glasses after every ride / wave etc., and I have tried anti-fog cleaning wipes & spray but they all just don't really work & spitting on the lens does not work also. I know now is the worst time for fog & condensation because of the cold water and early morning sessions but there must be something I can do, please help with any experiences & suggestions etc:-)

I had the same problem until bought a pair that look like mini googles that were a bit to wide and did not conform to my face. By having them further away from my face it let's the wind circulate around the lens and they rarely fog up. Of course they do not look great but it works for me.

Are they fogging because you're riding hard? Or fogging up because you've fallen in?

I have never had glasses fog up while riding, always from falling in.

If they've fogged after a fall I take a short breather sitting on the board, angle the edge of the glasses so they funnel the wind, and maybe lift the edge up a little. They usually clear within 30 seconds or so.

If I'm working super hard and falling a bit and the glasses have become a nuisance I push them down around my neck and keep riding without them.

If you're frequently falling after a wave ride, try getting the wing powered a bit earlier so you've got an easy carve to pull out and ride away.

If the waves are a bit crap consider riding with one or both hands on the strut handles and holding the wing so it doesn't have much power. That makes it easy to transition between wave and wing power when you need to and reduces the chances of falling.

I have been wearing surf glasses for around 20 years now. Oakley water jackets, Sea specs & RAVs were good. Some other brands the lenses popped out after getting dumped by waves. I just won't pay heaps for a pair if the chances are high at losing them. I recently lost a pair of RAVs because one of the arms popped out of its fitting. My next pair they were glued in place. All good.
In the last year I decided to ditch all of the anti fog solutions. They do not last. Even toothpaste & Baby shampoo. I also think that some lenses do not fog up as bad as others.
Surprisingly I have gone back to. Yes my saliva. No different to the solutions. And I have it while surfing.
What I have noticed is that within an hour of surfing my glasses seem to fog up less. Why? Maybe because a film dries on the lenses. I noticed this film on my lenses before I surf again. So before a surf I rinse them in fresh water, spit on the inside lenses, rub around with finger & quick rinse & shake off water droplets for better vision. My lenses are nearly dry by the time I hit the water. But the lenses will fog again after being submerged. When it gets annoying I will spit & rub again. After a while I don't seem to do it as often.
I really think to this date there is no fool proof way of having antifog lenses.
Obviously on windier days, warmer days & when moving at speed there is much less fogging. For me. Wing foiling, the problem is rare. Sitting on a board waiting for a wave after a hard paddle will fog up my lenses easier.
Yes. Cold, body heat & more enclosed lenses can be a problem.

I have had some success with Smitty's Glass Wax. Ordering sunglasses with hydrophobic coating (I use Zenni) also seems to make a difference. But details are foggy because it's been a while since I've gone out in really cold weather.
I still sometimes have visibility issues when sailing in extremely dry conditions, where drops on sunglasses dry out very quickly, leaving salt crystals on the glasses. The hydrophobic coating helps with that, since drops tend to fall off. Wax should be similar. But dunking the glasses is still sometimes required.

Great thanks for all the advice guys, I will be trying some of them out in the near future:-)