There are two (or even three) sets of drawings required to build a house. To start the process one draws up the Planning drawings. These show elevation and plan, and have to be to a particular scale (normally 1: 100). You can go and see any number of these by asking to inspect the Planning Application for particular houses at the local council - they are public information. The house design may be copyrighted but you can generally get enough detail to adapt for what you want.
The second set are Building Control drawings. These explain to the Building Control officer how your house will meet minimum stds for safety, structure and insulation (amongst other things). These are drawn up by an architectural technician (or architect). Just having any old set probably won't help you - you need a good understand of the various Building Control regulations to annotate the drawings with either specific dimenstions or be able to quote the BS spec. Sorry, but its really a job for a specialist. The things to be dealt with are:
Foundation structure, structural calculations for key components inc roof, insulation method and thermal calcs to show it meets stds, drainage and soil pipes drawings, ventilation, meeting the disability regs, fire safety regs.
In some cases, a third set may be required to tell the builders to how exactly to put something together - otherwise they tend to do their own thing.