Yes, most of the time we can have somebody over the same day to resolve your problem, however during exceptionally busy periods this may not always be possible.

No, not if they are careful and follow the simple rules to securely isolate electrical equipment, and check it is dead before they start work. If you received an electric shock but were not injured then you were lucky. Next time a slight change in events may lead to a very different result. No-one is immune to injury from electricity.

For more information, see:
Electrical injuries
Electrical safety and you
Electrical safety and you (Welsh version)
Electricity at work: Safe working practices

You can find out if your electrical equipment is safe by carrying out suitable checks, such as inspection and / or testing. The level of inspection and / or testing should depend upon the risks. A simple visual inspection is likely to be sufficient for equipment used in a clean, dry environment. In addition, equipment that is more likely to become damaged, or is operated in a harsh environment, is likely to require more demanding electrical tests. For further information, see: Maintaining portable and transportable electrical equipment.
Checks should be carried out often enough to ensure there is little chance the equipment will become unsafe between checks. It is good practice to make a decision on how often each piece of equipment should be checked, write this down, make sure checks are carried out accordingly and write down the results. You should change how often you carry out checks, according to the number and severity of faults found.
The best way to find out if specialised equipment is safe is to have it inspected and tested by a person with specific competence on that type of equipment. This may be the original manufacturer or their authorised service and repair agent. A reputable servicing company that deals with that type of equipment should also be competent to check its safety.
For more information, see: Electrical safety and you, or the detailed guidance in: Resources.

A wide range of voltages can be dangerous for different reasons. A very low voltage (such as that produced by a single torch battery) can produce a spark powerful enough to ignite an explosive atmosphere. Batteries (such as those in motor vehicles) can also overheat or explode if they are shorted.
If a person comes into contact with a voltage above about 50 volts AC, they can receive a range of injuries, including those directly resulting from electrical shock (problems with breathing, heart function etc); and indirect effects resulting from loss of control (such as falling from height or coming into contact with moving machinery). The chance of being injured by an electric shock increases where it is damp or where there is a lot of metalwork.
Electrical or thermal burns can also occur from the flow of electrical current or hot surfaces, see: Electrical injuries.

A person can demonstrate competence to perform electrical work if they have successfully completed an assessed training course, run by an accredited training organisation, that included the type of work being considered. As part of that course, this person should have demonstrated an ability to understand electrical theory and put this into practice.
A successfully completed electrical apprenticeship, with some post-apprenticeship experience, is a good way of demonstrating competence for general electrical work. More specialised work, such as maintenance of high-voltage switchgear or control system modification, is almost certainly likely to require additional training and experience.

Issues of competence are covered in:
Memorandum of guidance on the Electricity at Work Regulations 1989. Guidance on Regulations
Electricity at work: Safe working practices
Electrical safety at work: Resources

You can do your own electrical work if you are competent to do so. Simple tasks such as wiring a plug are within the grasp of many people but more complex tasks, such as modifying an electrical installation, may not be.
It is particularly important that anyone who undertakes electrical work is able to satisfy the requirements of the Health and Safety at Work etc Act 1974 and the Electricity at Work Regulations 1989.
For work on electrical installations below 1000 volts AC, you should be able to work within the guidelines set out in BS7671 'Requirements for electrical installations. IET Wiring Regulations. Seventeenth edition'. For details, see: British Standards Institution link to external website. Other work should be carried out according to the guidelines set out in the relevant industry standard.
Those who wish to undertake electrical testing work would normally be expected to have more knowledge and be able to demonstrate competence through the successful completion of a suitable training course.
More complex electrical tasks, such as motor repair or maintenance of radio frequency heating equipment, should only be carried out by someone who has been trained to do them.

issues of competence are covered in:
Memorandum of guidance on the Electricity at Work Regulations 1989. Guidance on Regulations
Electricity at work: Safe working practices
Electrical safety at work: Resources

It is the responsibility of everyone to make sure that work is safely undertaken. Managers have a responsibility to provide the resources, instruction and training necessary to enable their workers to work safely and in a manner that does not endanger others. Workers have a responsibility to make sure they keep themselves and others safe.