Is it necessary to reserve tickets now for the last week in April?
It would be a good idea to reserve tickets for the Uffizi and the Accademia museums - they are extremely popular.
What website do I go to?
Accademia w/ David
Website: https://www.galleriaaccademiafirenze.it/en/
Tickets: https://www.galleriaaccademiafirenze.it/en/tickets/
Uffizi
Tickets: https://www.uffizi.it/biglietti
Both are for timed entry. If you are going to be in Florence for a few days and want to see Bobili Gardens and Pitti Palace after the Uffizi consider the PassePartout 5 Days which gives you five days to see them after the Uffizi
Florence is amazing, enjoy,
=Tod