no contact due to lockdown

[asti]

Hi, I have a bit of a confusing set up, I live with my 3 year old and my ex husband has my 5 year old and my 14 year old (who is his step son). there is a court order in place saying the boys are to spend every other weekend with me. he drives them down as I do not drive and they live 48 miles away. the ex also use to have the 3 year old the weekends the boys weren't coming to me by arrangement we agreed ourselves. now I have not seen my boys since lockdown in late march with the ex telling me we can't. I understand that children can still be exchanged between the parents home. but considering the distance between us I don't know for sure if this still stands. It's hard because the ex husband is very worried and scared of catching this coronavirus and has been a little hostile when a few weeks ago I mentioned about seeing the boys. Could anyone please tell me what is actual law regarding this? Thanks in advance.