As someone who owned two studios in the past, one here in Swindon and one in Birmingham my advice would be to purchase the best lighting system you can afford as it will be abused at some point. Sadly not all photographers who hire studios look after the equipment and trust me, you will get breakages so you will require spares, this will include lights, modifiers, backdrops triggers etc. My Birmingham studio was 2000 sq ft where the main shooting area had vinyl backdrops....... hard wearing and easy to keep clean, down side it costs a packet. We did shoot on paper as well, six coloured rolls on a frame and levied a charge of £8 a meter if it got dirty or damaged.
Other costs you will need to consider are a good marketing budget, insurance, business rates, utilities and paying someone to managed/run the studio. We operated from 8am until 10pm 7 days a week so be prepared for some long days, as occupancy rates are highest during the evenings and weekends.
Best of luck in this new venture.
Ian