You should check with your local plumber the cost of the average job, how much their charging hourly rate and how long the job. The final plumber cost is a combination of the time taken and work and costs of the parts.
It also depends how big the plumbing job is going to be. Fixing a leak tap obviously going to be a lot quicker and cheaper than replacing a standard hot water tank.
Most plumbers will charge between £20 and £40 per hour, but the total cost will depend on the work.
A local plumber will usually give you their hourly rate. However, many plumbers give price after seeing the property.
Prices vary depending in the UK, London and other regions are more expensive than other areas. Bear in mind that the final plumber cost will be dependent on travel and transport access and parking charges.