Short answer: no, not legally. There is nothing in the planning system that says drawings must be produced by an architect, and councils do not ask. Whether you want one is a different question, and it depends almost entirely on how complicated your project is.
What the council actually needs
A householder planning application needs accurate, properly scaled drawings: existing and proposed plans, elevations, a site plan and a location plan, drawn to the conventions the planning officer expects. What it does not need is a signature from a particular profession. A well-drawn set from a competent draughtsperson is assessed exactly the same way as one from an architect's practice.
When a drawing pack is the sensible route
For a straightforward, well-understood project, a drawing pack does the job at a fraction of the cost. That covers most of what homeowners actually build:
- A single-storey rear or side extension
- A loft conversion with dormers
- A garage conversion or outbuilding
- A porch, or a change to windows and doors in a sensitive area
- A retrospective application for something already built
When an architect earns their fee
If you genuinely do not know what you want built, an architect is worth every penny — design is the thing they are trained for, and a good one will find possibilities you would not have. The same goes for a structurally ambitious project, a listed building, or a scheme where you expect a fight with the planners and want someone to run the case.
The mistake to avoid
Do not confuse planning drawings with building regulations drawings. Planning permission decides whether you may build it; building regulations decide how it must be constructed. They are separate approvals, and an approved planning application does not clear you to start work.
Deciding
Be honest about which project you have. If you can describe what you want built in a couple of sentences and it is a shape the council sees every week, a drawing pack is very likely all you need. If you are still working out what the building should be, pay for design. See what each pack includes and work out which fits.