Hi,
The Flat Rate Scheme is the main scheme which is designed to help smaller businesses. You can see the requirements for being able to stay on the Flat Rate Scheme here:
Leaving the scheme
If you cease to trade or your tunover is forecasted to be below the deregistration threshold over the next 12 months then you can deregister from VAT. Please see the guidance here:
Compulsory VAT registration cancellation
If your business picks up then you can choose to register for VAT at any time. You can see the guidance here:
VAT: an introduction
Thank you.