Thankyou very much for the response to my questions ,it was much appreciated,i am now a bit clearer on the situation and see you soon,looking forward to showing my work.  Tony

Hi Tony,  welcome to Bigartspace!
Here are some details on Copyright and taxation specific to the UK with some links to more information on external web-sites.
The Copyright of your work remains with yourself and not Bigartspace.   Copyright is an automatic right when you create the work.   For more information you can review this UK law Copyright factsheet 
Also,  for suggestions on how to protect your Copyright after a sale,  take a look at this Artist's Copyright FAQ
We do not currently automatically watermark the artwork on display this is because we feel it detracts from the work on display.  However, artists' are welcome to add a watermark to their own images before placing them on Bigartspace.   Here is a link to a useful article that explains the options: http://cameras.about.com/od/printing/ss/watermark_2.htm , and free watermarking service http://picmarkr.com/
Regarding taxes, (quoting from the UK Government web-site) certain types of asset are exempt from CGT including personal effects or goods which are individually worth less than £6,000 when you dispose of them and you only have to pay CGT if your total chargeable gains for the year are more than £8,800 in 2006-07. 
For more information see the HM Revenue & Customs Factsheet on Capital Gains Tax when selling online
Disclaimer: The information given here is given for guidance only; you're advised to consult a copyright lawyer on copyright issues and your local tax office for tax issues.