hi and welcome,
White patches on the throat mucosa is mostly due to bacterial infection like streptococcal or sometimes viral like herpetic ulcerations.
These ulcerations heal with time if there are not infected, it normally takes 7 to 10 days for the lesions to subside.
i would suggest you to maintain good oral hygiene
to prevent super infection that will help fasten the healing.
use antiseptic mouth wash like chlorhexidine
for mouth gargling regularly.
avoid too cold
or hot and spicy food stuffs , avoid smoking
and alcohol, drink lot of water and keep yourself hydrated.
i hope this helps ,