Is it the STV you're applying for? Just book a no deposit completely cancelable accomodation on booking.com or similar. For the flights you can go to a site that does booking itineraries which are confirmed flights that lapse after a few days, will cost you about £15. I did both those things and had my visa approved within 48 hours
Did you pay for a tourist e visa? If you did then immigration stamped you in wrong. Print out your e-visa and go to immigration asap. If you didn't pay then you were only going to get visa exempt and you'll need need to go to immigration anyway to get extended