Don't worry about the 90 days deadline, because of Covid, you can still go for Biometrics with the same letter active/expired. No need to send a web form as well. I had raised a webform earlier to seek clarification and this is what I had received as their response:
Biometrics
Some biometrics collection sites are currently closed. If the site closest to you is closed, we'll automatically
extend your deadline to give your biometrics. You don't have to give your biometrics
until the sites reopen. This applies even if your biometrics instructions letter (BIL) indicates that you have 30 or 90 days. You don't have to contact us to request this extension and you don't need a new BIL to make a future appointment. Once the sites start to reopen, make an appointment as soon as possible to avoid delays.
For more information on the situation and to receive up-to-date information, we invite you to verify our
website.
We hope the information provided is helpful in assisting you with your enquiry.
