Thanks to all who have shown an interest in this post. I have now bitten the bullet and booked my crossings for next year. I was concerned that when Brittany Ferries realise the high priced being charged by P&O, added to the possible delays at Dover, their prices may rise accordingly.
I have still paid less for next year than I did this year so there's a bonus.
Don't forget to leave a review of the French and other European campsites you have visited!