I did it for the whole lot because I’m cancelling it anyway. I’ve actually done my flight and accommodation based on 90 days so hopefully they don’t knock me back for that. I’ve always done it that way on a tourist visa in the past
The Embassy in London emailed me to say a one way ticket is fine because I said I’m unsure of the exact date I’d be coming home 👍. In terms of accommodation just go on Agoda and find a hotel that offers “pay at hotel” and book it. You will then get a confirmation sent to your email which you can use for your application and then cancel it 👍. Then you are free to book what you want, when you want and where you want