I think it may depend on whether you will rebook for a later date, you can apply your deposit to another booking if you cancel the first one but I don't know what they would do if you just cancel altogether you may lose it all.
do you think they'll let me transfer it from disneyworld.co.uk to disneyworld.com? i'm not going to cancel full stop but i would be looking at transferring it to disneyworld.com if free dining comes out.
I don't think they would let you transfer it but I'm not 100% sure, why don't you give them a call to be certain? I've never heard of anyone transfering before although you can amend your booking for if I remember correctly a 25£ charge. Not sure on the rules regarding that though. I usually book with .com but this year it works out much cheaper to go with the UK site but I understand wanting to wait to make sure you get the best discount. Good luck!
one more question, if i book a package but then cancel, but still want to apply my £100 deposit to a couple of nights room only, will i be able to do that?