A typical project may consist of the following:
Conduct onsite measured survey of existing dwelling, plus garden boundaries.
Prepare scaled plans of the existing:
(a) Ground floor plan;
(b) First floor plan;
(c) Elevations;
(d) Site plan showing garden boundaries;
(e) The above would usually be at 1:100 scale.
(f) Obtain ordnance survey map usually at 1:1250 scale.
Prepare scaled Planning and Building Control drawings of the proposed:
(a) Ground floor plan at 1:100 and 1:50 scales;
(b) First floor plan at 1:100 and 1:50 scales;
(c) Elevations usually at 1:100 scale;
(d) Site plan showing garden boundaries usually at 1:100 scale;
(e) Section’s through existing and proposed at 1:50 scale;
(f) Roof and floor timber plans at 1:100 or 1:50 as necessary;
(g) Structural calculations;
(h) Constructions notes.
Complete and submit Planning and Building Control forms and submit applications.
Liaise with Planning and Building Control departments and amend Plans as necessary.
Communicate with Thames water on your behalf if necessary.
Advise / provide you with Party Wall Act notice etc.
There can be other work involved such as Highway issues and perhaps an appeal to the Planning Inspectorate etc.
The main point is that I do not charge until all of the above has been completed, and you have your approvals!