Ok, your tide tables are correct. Check against this...
http://easytide.ukho.gov.uk/EasyTide/Ea ... onLength=7
It's a full moon (near enough) so should be about full springs which should give you the greatest range of tide.
However, wind and air pressure can also have a significant effect on actual tide height at any given time. Very low air pressure will cause the tide to be higher than normal. Similarly, in a bay or inlet, a strong onshore wind can 'heap' the water onto the shore. In fact, in any enclosed body of water like the Irish Channel or North Sea, you can get significant storm surges in really bad weather. Check this out....
http://en.wikipedia.org/wiki/North_Sea_flood_of_1953
For digging bait, most people go out an hour or more below low water and follow the tide down to get the most time before the tide rises again.
Just like gambling your life on a weather forecast, never depend on the tides to follow the times or heights in a tide table - paricularly if you are fishing or collecting bait on a bar or spit where you could be cut off by a rising tide.