Yes it’s OK to work on Holy Saturday.
Lent - starts with Ash Wednesday (distribution of blessed ashes). Day of fast and abstinence from meat. EVERY Friday during Lent is a day of abstinence from meat.
Next day of note is Laetare Sunday (fourth Sunday of Lent - priest wears, if possible, rose rather than purple vestments).
Then Palm Sunday (procession with blessed palms, reading of the Passion from the Gospels).
Then Holy (Maundy) Thursday - usually in the morning there is, in each diocese’s Cathedral, a Chrism Mass where the holy oils are blessed by the bishop for all his priests for the next year although this can be any time around Holy Week.
In the evening will be the Mass of the Lord’s Supper (washing of the feet, and procession with the Eucharist to the ‘altar of repose’, the tabernacle being deliberately kept empty until Easter Vigil.)
Good Friday - day of fast and abstinence. Stations of the Cross at some point during the day, liturgy commemorating the Lord’s passion, usually at 3pm - with veneration of the Cross.