Thank you for all the information, help and advice over the past few days, it's all very much appreciated.
I think instead of rushing straight into a purchase I will go to a few meets, first starting with NHAEG on Mon 14 Aug.
I appreciate the Opal on EBay is not in showroom condition but at present I'm just looking for a mechanically sound 7 as a starting point. If any of you do know of anything suitable then don't hesitate to message!
You sound like a wise person, I would strongly suggest that you get someone who knows their sevens to go and look with you at any potential cars.
As already earlier said an honest scruffy car is a nice start.