Hello, /r/RealEstate! I hope you can offer me some advice on the flat I am hoping to purchase.The mortgage has been approved subject to an assessment of the property by the bank and if all goes through and no one else makes an offer, within 6-8 weeks I will hopefully be the owner of a one bed, one bath top floor flat with a loft. The loft is only accessible through a panel in the bedroom ceiling so we haven’t seen it yet, and the realtor doesn’t have details about it either. The property is a repossession and has been vacant for quite some time.The plan is to fix it up and rent it out while I am studying and use the rent to pay the mortgage. If, however, it is possible to convert the loft into a second double bedroom with an ensuite bathroom, I think it would be worth doing so in order to maximise the rental potential, and then in a few years time when I move back down, I will be able to live in one room and rent the second room.When I visited the flat there were a few major changes that I wanted to make, and the lady who showed me said that it should be fine, but was not 100% sure and said that I’d have to check with the relevant authorities. I want to:take out the wall between the kitchen and living room making it open plan (it is not a load bearing wall, it is hollow when you knock on it) andget a new boiler to replace the huge boiler taking up an entire little closet, and get rid of the closet to make the kitchen bigger.Additionally, I’d really like to replace the windows with double glazed and much larger windows to let light into the bedroom, living room and kitchen. Do I need special permission for this?Convert the loft into a double bedroom with en suite bathroom, putting a load of windows in the roof because there are currently none and without windows, it would be a fire hazard/caveTo put stairs in, there’d have to be a small staircase put in in the living room to access the loft and for fire safety, there’d have to be windows put in up there in the roof. I am concerned that this would be problematic to get permission for, and I don’t know who to get permission from or to enquire with.Can anyone offer me any advice? I’m not really totally sure what I am doing.tl;dr: How do I find out if I am allowed to put in bigger windows, tear down walls, and convert the loft in a leasehold flat that I am purchasing?