My understanding is that the Govt brought in a directive that companies have to let their employees carry leave over (for up to 2yrs I think?) if they are unable to take it this year.
I am guessing it will apply to most furloughed employees (I am sure that they continue to accrue leave during furlough) but maybe not those working normally.
My company (an engineering consultancy) are operating as normal, apart from some office staff who are furloughed (all offices are closed). We can normally carry over up to 5 days, but only in exceptional circumstances and with director approval. I am hoping that ruling may be relaxed, but I am certain that there will be no leeway to carry over more days. The company wont want everyone to have excessive leave next year.
We are planning a week off in June, to have a break and hopefully do some long dog walks, then other weeks in the autumn, when we maybe can take our caravan away.