Ask most plasterers and the answer is builders, word of mouth, and whoever rings. That works, until the builder you rely on has a quiet quarter and takes you down with him.
The direct domestic work — a homeowner who has just pulled the artex off a ceiling, a landlord with a damp patch, somebody rendering the front of a house — is steadier, pays better per day, and almost all of it starts with a search. Those people do not have a plasterer’s number. They are typing one into a phone, and whoever comes up with photographs and a straight answer about price gets the call.
You do not need a big site for this. You need five clear pages, real photographs of your own work, and to be findable in the towns you actually cover. That is the whole job.