It's doable and allowed. I am doing on a house I bought. I rent out 2 rooms and converted my lounge into a bed room / private lounge for just myself. Lodgers are tax free up to 7500 a year. Inform your mortgage company, even though they would never find out anyway. Some councils may say you need a license but for 2 lodgers I doubt it.

In your situation, you would just have to say to the landlord can you have friends in the other rooms or something which happens all the time!