Sorry to hear about this. Can I suggest that if you do not get any immediate offer of a new home for these fellas to contact your local vets to see if they know of anyone. They may even put a poster up in reception for you (er, of course, if that is what you would be OK with). We get the occasional person in at work who specialises in keeping a particular type of pet.
Oh Dear Jo.
So sorry to hear you news.
They aren't easy to re home I am sure. As Bluebell says get onto the vet. I am sure there will be a society that will help you out and the vet may know of one. I know there is one for tortoises so there must be for terrapins. Have you looked on the internet to see if there is any.
Good luck with your quest, they are dear little things.
Wendy