If you wish to find out more, there is abundant information on the web (type "Chalara" or "Ash Dieback" into a search engine) or for the most up-to-date information go to the webcasts of a conference called "Living with Ash Dieback in Continental Europe", held at the Linnaean Society in London on 29 November 2013. http://www.youtube.com/channel/UCI810ZkJIgiS9ALeeT5tq3g
In all, there are more than 6 hours of footage, with 23 papers.
The opening address was from Lord de Mauley, Parliamentary Under Secretary of State for the Natural Environment and Science, then there was a series of talks from eminent scientists from across Europe.
For modelling the likely spread of Ash Dieback across the UK, see the paper by Professor Chris Gilligan of the University of Cambridge starting at 38 minutes into the webcast of Session 4. (http://www.youtube.com/watch?v=3eBKXElvVxQ)
This is a brief paper, lasting only 10 minutes. Towards the end, he shows some slides which indicate that before the end of the decade we will have Ash Dieback across England and Wales.
In case one got too depressed by the preceding papers, the final presentation was by Professor Steve Woodward of the University ofAberdeen on the Emerald Ash Borer beetle which is heading our way. He says that if Ash Dieback doesn't get our Ash Trees, they'll be food for the Emerald Ash Borer.