You do know their are STR regulation in London and you can only let your place out for up to 90 days a year don't you @Nader40
No-one can answer whether it's worth. That depends on multiple factors including what you would do for the other 9 months of the year, your costs, charge out rates etc.
Some just carry on letting illegally - some do long term lets the rest of the year.
If you want to get into the short term rental business the first thing you should do is check if there are any short term rental legislation in the area you are interested in. @Nader40