Only answer - Yes. 

It is a misconception that your Building Control service has to be acquired from your Local Authority.  Nothing wrong with these chaps, but the system was privatised several years ago and myriad Building Control offices were opened over the country that can supply you with a Building Control Officer for a fee.

These offices, as well as those within the Local Authority offer two building control services to oversee your construction :

a) Building Regulations Drawings 

b) Building Notice. 

The former requires detailed drawings of every aspect of the build - foundations, drainage, utilities, walls, roof, fire alarms, materials used.  Everything.   You submit these to the Building Control office along with your fee to pay for both the checking of the drawings and the visits of your Building Control Officer (BCO).

The office inspect these drawings and approve them in full or subject to conditions (such as structural calculations for the timber frame).  This process takes up to eight weeks - BUT, 24/48 hours after you have sent them in you can use them to start work and ask the BCO (Building Control Officer) to visit site to inspect your trenches (which of course are the first thing that is generally done).  It can be the case that Building Control sign off the groundworks and even the timber frame is erected before you get your approval of your drawings (with or without conditions).  

The alternative route - quite common for smaller builds - is the Building Notice.  In this instance, Building Control is informed that you are starting to build and you pay a lesser fee than for the drawings and visit fee; and you can ask the BCO to come to site to inspect your ditches once you have completed them.  You will then discuss with your BCO what you are doing next, how you intend to complete that phase and schedule when he/she should next visit for their inspection.

In general the BCO visits to inspect the trenches for the footings and drainage/services, returning to inspect

the damp proof membrane (DPM), damp proof course (DPC) and then the insulation in the roof/ceiling.

They don't make too many visits but when they do, the BCO is generally a very helpful individual.

Back to the question "are building regulations drawings needed" and to the longer answer Yes. 

Whoever is building your "building" needs to know what it looks like - so at some point, to some degree of accuracy, you will need technical drawings.  Drawings provide foresight - this is how to avoid problems.   And for a build more complex than the addition of a living room extension to your house (with no plumbing or drainage required) foresight saves money.

Shortest answer is No. 

All of the above applies in that Building Control are overseeing your project because the build has to be signed off as meeting Building Regulations. To show that the building is safely constructed with all due consideration to the requirements of the Regulations.

Drawings for a BCO to check through and sign off are not necessary if you are fully in control of the work being done, able to keep everyone on site fully informed as to what is required, and you know when BCO has to be on site to check the work.  Or of course, if you are making it up as you go along.......

Drawings are needed if you are leaving the build to a main conttractor to complete with little interaction from yourself until the decoration starts.  Without clear instructions, the builder wont know what you want and will probably make it up as they go along - because what else can they do?

The Regulations drawings are sort of crib sheets for the builder who knows what he is doing, making sure nothing is missed.  Adding where the lights, switches and sockets go, the heating system, heat recovery, air source heating is also critical stuff if you are not there.

So although the shortest answer is No - think about what your own input is and what you expect from others then draw an appropriate conclusion for yourself.