Hi John, first up you need to understand the variations. You say you are looking for an XK8, which goes by the model designation X-100. Then you indicate you would like a model from around 2010, which would be the X-150 model.
The X-100 was built between 1996 and 2005, whereas the X-150 model was built between 2006 and 2014 / 2015. For 2010, you would be looking at a 5.0 litre engined car, available as either a Coupe or Convertible. My preference is the Convertible, but to each their own. There is also the choice, in both models, for the naturally aspirated XK8 / New XK, or the supercharged XKR.
The X-100 is a steel bodied car, with specific areas prone to corrosion that you would need to be aware of, whilst the X-150 is an aluminium architecture and body, with minimal corrosion elements, but still needs to be carefully checked.
There are quite a number of good You Tube videos on the merits of the X-150 which you could seek out, but the best advice is to go and see as many cars as you can locate to get a "feel" for them. If you are a Jaguar buying novice, then try and take someone with you who knows what they are looking at. The X-150 cars are typically available these days from circa £10k to +£30k and obviously you get what you pay for.
There are currently 18 X-150 cars for sale on the JEC Classifieds, the JEC is the largest Jaguar Club in the world. The link below should take you to the list of Classifieds at the JEC site. There's also lots of other information there, but most of it only accessible to the members, but worth the fee in my opinion.
jec.org.uk/classifieds/index.php?page=cars-for-sale&category=1608
Simple adage, buy the best you can afford, but keep your eyes open and seek advice if unsure. The JEC can arrange for inspections by local enthusiasts' knowledgeable about the particular model, but again I think that needs you to join the Club.
If you find anything of interest meantime, come back here and post a link thta folks can check out on your behalf.
Good Luck.
N6 JMX