Buyers have bidder on my items and want me to send abroad.

[mmmmmchocolate]

I've never done international postage and have only listed my items in eBay uk.

I don't want to complete these sales now and just give the buyers their money back. One has just paid and paid for (the rather cheap) uk postage.

Can I cancel these transactions, without them being able to leave me neg feedback?

Yes refund and cancel with email saying you don't send internationally.

Then make sure you set up restrictions correctly when listing!

I listed on my phone so that could maybe be why they were able to? Usually they are blocked but I still always get emails asking to send abroad.

Yes that should be fine. Next time you post more things just make a little note to say that you don't post abroad (although you will probably still get messages from people asking) xx

you will have to tighten up your settings so people can't bid from abroad in future too.

You will need to go to the resolution centre to cancel transaction to get your fees back