There is no universally right answer — but there is a right answer for your stage, budget and the skill you are buying.
Freelancers
Best for: single-channel needs, tight budgets, businesses that can manage the work directly. UK day rates run £250–£600 for good specialists. The risk is capacity and single-point-of-failure: when your freelancer is ill or fully booked, nothing ships.
Agencies
Best for: multi-channel programmes, faster scaling, and access to senior strategy without hiring a team. You pay for breadth and process. The risk is being a small fish — check whether your account size gets you A-team or intern attention.
In-house
Best for: when marketing is a core competency and you can afford £35k–£80k+ per head plus tooling. Maximum control and context, but one hire rarely covers strategy, execution and analytics.
The hybrid that usually wins
A senior in-house lead owning strategy, with agencies or freelancers supplying specialist depth, is the model most scale-ups land on. Use AgencyScore to find partners comfortable working this way — the best agencies say so on their profiles.