"if there are others in England," - here's a link to the Folk Roots list (and this doesn't include lots of smaller ones.)
If you can get a ticket, Cambridge can be a great weekend. Even for people who aren't that into folk music. (In fact it's when people are really into folk music they tend to put Cambridge down. I don't agree, because it's a different type of festival, and has its own good qualities.)
Here is a link to the OysterBand's website, which has tour details; Atlan? Well if that's a typo for Altan, here is their website.