The only reason I am not going on holiday is because I have to work. WORK. If I ............... ............................ I’d go on holiday.
If I ...............didn’t / have to work, ............................ I’d go on holiday.
If you don’t want me to, I won’t mention your name. UNLESS. I won’t mention your name………………………………….
I won’t mention your name……………unless you / want me to…………………….
Lizzy advised Alex to take an umbrella. WOULD. “Alex, if…………… …………….. take an umbrella,” said Lizzy.
“Alex, if……………I were you, / I would …………….. take an umbrella,” said Lizzy.