Flat roof to mono-pitched or lantern?

Neither of theses are cheap, but the cheaper would be the roof lantern. The cost will be thousands minimum £4,000 for a roof lantern, once you factor in the lantern, structural timber works, plastering, and weathering the kerb trim. I installed three roof lanterns last year into pre existing holes, eg removing old lanterns and fitting new and the cost from my stage of works was £10,800 including VAT alone, and that was before plastering came into factor. You may need carpenter, roofer & plaster for this job, or you might get lucky and find a good roofer who can do both carpentry works and roofing, so then you only need two trades. regards Frankie BT Roofing Services Limited

All depends on style, size the all very will defo let a lot of light in regardless but definitely not a cheap fix anywhere from 4k on wards