Absolutely guests are not going to want to arrive in a strange city and have to find a key store first and then make their way to your listing.
you could meet guests on arrive and handover the keys.
it's exceptionally risky in London to leave your key under a pot. Not only do you risk being broken into but you put other residents in the block at risk .
And please revise how you respond to guests who have been complaining about cleanliness , broken items at your place, lack of locks etc.
it will certainly put other guests booking with you .
you should be factual, calm and polite.