If you tried to buy a cream tea in a cafe in St. Ives with a £50 note not only would you be deeply unpopular but chances are they wouldn’t accept the note. We even say that you can spot a tourist as they have wads of £50s. If when you get your holiday money you see a load of €100 and €200 notes then you are not going to be happy. The reality is that these large denomination Euro notes are not a problem to spend. All of Europe is far more cash based than we are and their banks do not punish the small traders when they do discover a forged note (which is extremely rare) which is what UK banks do. If a small business here hands over a forged £50 note then it is the small business that takes the loss. That is why they don’t want these high value notes.
Over in the Eurozone though cash is used far more frequently than it is here and that means that the trader or cafe wil be holding a lot of cash and a lot of notes of all denominations. Believe me changing your €100 will not be a problem. This is a very British attitude and one you can lay to rest as just one of the things that the Europeans laugh at us about; a bit like drinking too much and falling asleep in the sun, another stereotypical British trait.
In my opinion I would rather have a €100 note in Paris than a £10 Scottish one in Penzance. You’ve got more chance of getting it accepted.