Later afternoon is preferable.

The UV is at its highest during the middle of the day and sunburn is more easily gained.

Don't be fooled by cloud cover either, just because clouds are there, does not mean that the UV rating is lessened. Many people fall for this, going out between 11am and 3pm, and end up with horrible sunburn, thinking that because the sun is covered that there is no UV danger.

Remember Slip, Slop, Slap and reapply sunscreen every hour if you are getting wet or overly active physically!

 I would go in the afternoon where Ratbag can have some time in the sun without a hat, and sunscreen..  Call me strange, but I was talking to my Dr about vitamin D ( which comes from the sun and helps with calcium adsorption) and she stated that you need to be in the sun at least 15min per day with out much clothing on..  ie: just bathers.  You need to have sun to skin contact for you to get max vitamin D.   

I had a blood test done the other day for my vitamin D levels and I came up at 37 not much considering that we all should be over at least 70.  So now I am taking vitamin D tablets

So after all that said I would go in the afternoon and put hat and sunscreen on and keep reapplying sunscreen until about the last 30min or so b4 going home so Ratbag can have some sun time without the sunscreen and his hat.   

 I think if you take Ratbag to the beach any time after 2pm, you will be fine! 

They say the hottest part of the day is between  10 am & 2 pm.

Remember to "Slip, Slop & Slap"

Have a great time, don't foget my vinegar with those chips! 

If you go to beach closer to lunch time make sure you reapply sunscreen every 2 hrs, rather every 4. The sea will wash off some of it plus the water reflects uv rays, causing 2x the amount of uv rays. Plus with daylight savings it is between 10 and 4 clock for the dangerous or rather the full intensity of the uv rays.

Make sure you apply sunscreen at least 3cm beneath clothing, and white clothes reflect heat, so a child will be much cooler if they wear white or pale coloured clothing

Cheers Raven