Drove up this morning. Left Worthing at 10.
30 minute stop and was here by 2.15. The a11 was crap too.
So, 4-ish hours by car, mid-morning on a Thursday.
On that basis, I reckon coaches leaving the south coast at 2pm on a Friday at the end of the Easter holidays is pushing it close. Hitting the Dartford Crossing anything after 3pm on Friday is usually the recipe for a complete clusterfvck.
Hope I am being overly pessimistic for all concerned.