In the UK, whether an online first aid certificate is considered valid largely depends on the type of first aid course, the specific requirements of the workplace, and the accrediting body of the course.

1. Type of Course: Some basic first aid courses can be completed entirely online, especially those that are informational and do not lead to a formal qualification. However, for more comprehensive courses like Emergency First Aid at Work (EFAW) or First Aid at Work (FAW), practical components are essential. These elements usually require in-person assessment to ensure competence in hands-on skills such as CPR.
2. Accreditation and Recognition: The validity of an online first aid certificate also depends on who has accredited or recognised the course. In the UK, first aid courses should be approved by a competent authority to be considered valid. The Health and Safety Executive (HSE) stopped approving first aid training and qualifications in October 2013, but they provide guidance on what a first aid course should include.
3. Workplace Requirements: Employers are responsible for ensuring that first aiders are appropriately trained. This includes making sure that the training is fit for the specific requirements of the workplace. In many cases, especially where the workplace is considered to be higher risk, online-only training might not be deemed sufficient.
4. Blended Learning: Some courses offer a combination of online theoretical learning and in-person practical assessments. These blended courses can be a valid form of first aid training, as long as the in-person component adequately covers the practical skills required.

It is always advisable for individuals and employers to check the specific requirements of their workplace and ensure that the chosen first aid course meets those needs. If in doubt, consulting with a health and safety professional or the organisation offering the training can provide clarity.

In the United Kingdom, a first aid certificate is typically valid for three years. This applies to both the Emergency First Aid at Work (EFAW) and the more comprehensive First Aid at Work (FAW) qualifications.

Upon expiration of the certificate, first aiders need to undertake a requalification course to renew their certification. It's important to note that:

1. Requalification Timing: It's advisable to requalify before the certificate expires to ensure continuous certification. If the certificate expires, the first aider may not be considered legally competent to act as a first aider in the workplace until they have requalified.
2. Refresher Training: The Health and Safety Executive (HSE) also strongly recommends that first aiders undertake annual refresher training. These are shorter sessions intended to keep their skills up to date in the interim years between the initial training and requalification.
3. Requalification Course Duration: The requalification course for FAW is typically shorter than the initial course. For EFAW, the requalification generally involves taking the full course again.

Employers are responsible for ensuring that their first aiders remain trained and qualified, in line with the Health and Safety (First-Aid) Regulations 1981. This includes keeping track of when requalification is due and arranging for appropriate training.