In reply to WeeTJ:
i do something broadly similar - i've a tent you could cook in, but its all a bit of a pain - i tried 'lashing up' something that covered the porch area and made a bigger space bit it never really worked. i just put a standard tarp up in the immediate area of the tent and use it as a cooking, mooching, living area and use the tent as the sleeping area or bolt hole in utterly foul weather.
for this kind of thing you only need a basic sheet with eyelets, some pegs, maybe a walking pole or stick, and some bungees and a bit of string and you'll be able to pitch up anywhere.
if you aren't fussy about colour, you can pick up a 2nd hand, 7ft by 8ft desert DPM basha sheet on fleabay for £10...