I opened up the plug and it was a mess- the earth wire was not connected at all which made me slightly uneasy as I'm not sure how long it was operating like that. So I rewired the thing and it still tripped the fuse. Not sure what's going on with the bulb and heater- whoever made the viv seems to have fixed everything in pretty well so I'm not sure how I'm going to remove the ceramic cage. I'll have a fiddle with it tomorrow.
Currently using a mat and stat so snakey is ok
Thanks for all the replies, much appreciated.