Government advice now allows travel to other places in England so you may be thinking of visiting nature reserves further afield. If you are a member of either the BBOWT or BCN Wildlife Trusts you will have received an up-date on the current situation on reserves access. If not, do check out the advice on their websites: https://www.bbowt.org.uk/covid-19-update and https://www.wildlifebcn.org/news/how-we-are-responding-covid-19.
In both cases most reserves are open, but car parks, visitor centres and bird hides remain closed.