RE: Magnetic hatches?!
Edmond scientific has some great magnets and I think they ship to UK.
[link]http://scientificsonline.com/search.asp?t=ss&ss=magnets&x=0&y=0[/link]
Also places like all electronics has a great selection:
[link]http://www.allelectronics.com/cgi-bin/category.cgi[/link]
Radio Shack:
[link]http://www.radioshack.com/search/index.jsp?kwCatId=&kw=magnets&origkw=magnets&sr=1[/link]
And you may want to click on some banner ads here at R/C universe a see if they have any.
Enjoy!
-J