Ensure that your loft windows comply with being fire escapes, or you will need fire doors all over the house.
The joists of your loft will need reinforcing with RSJ's, as the loft is not meant to withstand the weight of human occupation.
The Council will want to check your plans out for building regulation. You may also need planning permission, if you change the roof with anything other than flat windows like Velux.
If you try to do without planning permission and buiding regulation stuff, you will have trouble when it comes to selling the house as these changes are now looked out for in the searches.
Do not save on an engineers calculation for strenghtening the joists, or you will have forever cracking ceilings underneath if not worse trouble.
I would recommend you get a good firm of local builders to do all the structural work for you and then finish all the "prettifications" according to your skills.
We've done it this way 5 years ago and are very happy.
ATB and good luck
stentipede
