Idiot's Guide to building an extension

[wessex101]

Most good local designers do a free initial consultation. They will visit site and spend about 30 minutes chatting about your proposed extension and should be able to give you a very rough idea of what is possible.

If you want more in-depth advice to explore various different options you would be better off paying for a feasibility design.

 

[Footsoldier888]

OP you are saying above the roof is too flat for a loft conversion. However if you have the funds a new roof at a higher pitch is possible or if the foundations will allow it is possible to fit a ring beam and then add a second storey, subject to planning naturally.

A feasibility study could be a very good option for you.