Kate, this is obviously too late for your strawberries, but worth considering in the future.

See this site:

http://hitchhikingtoheaven.com/2012/03/making-jam-.....fruit.html

If you don’t want to spend your whole summer in the kitchen, the most practical approach is to freeze fruit in perfect condition in small, measured quantities, so that you can make jam as you need it throughout the year. Jam made from frozen fruit will taste infinitely fresher and more delicious than a six- or seven-month-old jam even if it is made in peak season.

Of course, it would be good to weigh it before freezing and note the weight, but on this site, they recommend that to defrost the fruit with the sugar will work best. I'm glad you asked the question, Kate, as now I think I may do this in the future, rather than spending so much time in the late summer - in the kitchen!! 

Good luck with your future jam-making!