I have been told to place a flower / rose nail into the pan in order for the cake to not dome, can someone please tell me what this is? Does it have another name in the UK?
are you talking about this??
http://www.bakedeco.com/detail.asp?id=8976&catid=392
you can use the nail if you don't have a heating core. 
Here's a photo tutorial for the flower nail method:
http://www.cakecentral.com/cake-decorating-ftopict-612603.html
HTH
-Rezzy
its not a cake nail but its called a cake core
Actually there 2 different things.
Here's the heating core:
http://www.wilton.com/store/site/product.cfm?id=3E30ACBE-475A-BAC0-505CDCE7A4EA25E5
Diane already posted the link for the flower nail.
The heating core creates a large hole in the cake that you have to plug up. What you do is pour batter into the "hole" and then use that part of the cake to plug up the hole (I hope that makes sense 
).
With the flower nail all you need to do is prepare it like you would your cake pan so the cake does not stick to it (I use homemade cake/pan release which is equal parts oil, flower and shortening - mix well). You can either place the nail in the pan and then pour the batter around it or you can pour the batter first and then place the flower nail in. Make sure you put it in upside down with the sharp part pointing up. If the cake is larger you can place more than one nail in.
HTH! 
Quote by @%username% on %date%
%body%