The loft conversion is supposed to bring value to your home either as a living space or in case you want to sell it. It is almost always preferable, when possible, to convert it to a livable space rather than a storage space. Especially when you are able to fit in there a bathroom and some storage space, it would make a perfect guest room or even master.
Prices for loft conversions can vary depending on the solution you are choosing, adding a skylight will be the cheapest solution but it may not work in case you loft doesn’t offer enough space. You may be more pleased with adding a dormer, to increase the surface and headroom, even with the increased costs. Changing the line of the roof with a dormer will especially when you make it the whole width of the roof will bring you the desired space.
Before starting your loft conversion you should asses the available head room, it should be at least 2.3 meters tall, and in case it is insufficient you either have the option of lowering the ceiling of the room below, or rebuilding the roof. Both options would mean increased costs and disruptions to your living. You should carefully analyze your options and decide for the best variant.
Some house have extra loft rooms, rather than bedrooms, this means the extra living space isn’t quite up to standards to be called a bedroom. There are certain building regulations to be met in order to be able to officially be called a bedroom. The main issues are having a proper staircase, insulation, windows. It is up to you to determine whether the costs and effort to convert the loft to be a proper bedroom will benefit you.