Unreal Conditional: Use бы + л in both clauses.
Since you have no choice as to what verb forms to use, you don't have to worry about the distinction between past/present/future or between hypothetical and contrary-to-fact.
Љсли бы Сђша не пришёл, бІло бы скџчно. If Sasha weren't here, it would be boring.
БІло бы плћхо, љсли бы Сђша не пришёл. It would have been bad if Sasha hadn't come.
Љсли бы ћн пришёл, мІ бы пољхали зђ город. If he had come, we would have gone to the country.
If he were to come, we would go to the country.
Љсли бы былђ вђнная, ї бы снялђ. If there were a bath, I'd take it.
Had there been a bath, I'd have taken it.