Lee
I would presume that solicitors must have some form of contigency plan, to ensure continuity of service when they are unable to work. The Solicitors regulatory authority on 0870 606 2555 ( 09.00 to 17.00, Monday to Friday) should be able to answer your query, http://www.sra.org.uk/sra/contact-us.page
I would give them a call on Monday and then inform all relevant people, that the purchase may be delayed due to the circumstances. I am sure they will sympathise, put things on hold and wait for further instructions.
I hope that all works out, without too much delay.
huckster