Great that you are thinking about the best course for your staff at such a difficult time. You can terminate staff by reason of redundancy where you have genuine business reasons for doing so, which it certainly sounds like you have. Before making any decisions, you will need to work through a consultation process which will involve, in short, putting your proposal to staff, providing them with any relevant information, discussing it with them and keeping an open mind to all possible alternatives. There is no legal issue with rehiring redundant employees in the future, but be aware that they will be under no obligation to accept any future offer of employment. There are potential issues with the legality of an unpaid stand down which you may wish to seek further advice on if you intend to continue down that path.
Happy to chat.