I got one for a tour of Europe (12 days) plus day in London
Oh you so need more then one day in London! Honestly you would be so rushed if you did that tour and would leave you really wanting more. I would save the tour of Europe for another time when you have more time to do it.

Or alternatively if you really do want to do Europe only pick 1-2 countries to do in that timeframe...you could do UK/Ireland in 2 weeks but you lose a day there and back in travel time, or even do Italy for 2 weeks - now that would be divine.