Well, you're virtually on neaps and hw is 13.52 at 4.1m so I would reckon on hitting the water at 12.52 if you want an hour. I've done it before and got in at HW. This did not seem to be the best time to dive. Have spoken to others since and an hour before is better on the flood tide.
Obviously, if you've done it before and prefer other times then ignore me. Just a warning too.
I had my drysuit/undersuit and bag nicked out of our van at Trefor by some scroats parked next to us in a campervan, looked like a travelling family or something, be warned.
If you don't get in there there is always Dotty, was there yesterday but the visability was affected by water runoff. If you do get there have a look in one of the blast huts, we put a microwave in there yesterday. Take your pies
Cheerio
Lyv