In reply to Sl@te Head:
> There will be a difference depending on whether it's a Spring or Neap tide....
And a Spring tide has nothing to do with the season of Spring! Interpreting tide prediction tables is not easy if you've never done it before. They vary every 24 hours, and are not absolute, hence they are predictions only based all sorts of factors like the gravitational pull of the moon, atmospheric pressures, wind strengths and directions, rainfall, particularly near river mouths.
If in doubt ring the coastguard before you set out, they are usually only too willing to offer help and advice. Even with a tide table I have rung them when contemplating doing a coastal stretch if only to double check with them and equally importantly to notify them of my intentions so as not to have well meaning cliff walkers and holiday makers ringing them to say that someone "needs rescuing" when you don't. They are very grateful if you do this and ask you to notify them once you have finished.