Thanks for the positive comments chaps!
Ice - The large pieces that form the bulk of the pit (two sheets of 15mm 8x4 and a sheet of 6mm 8x4) were cut by a company in Birmingham for a surprisingly low amount, it's worth shopping around for quotes - If you can draw your 'pit plans in a format that the CNC shop can use, that helps keep the costs right down.
HitchHF - The mini CNC is called a 'Tonsen I', I imported it from China for $580, which I think is a bargain - it's a fantastic tool, especially if you're into modelmaking etc. All the tooling was bought off various ebay sellers. The plan was to sell the CNC once the panels were finished to fund the new PC build, but I'm keeping it. (don't tell the wife!)
One of the best pieces of advice I could ever give somebody new to CNC - use Vectric software, it's fantastic. The learning curve for most of the CNC apps out there is scary. I really struggled at first, but Cut2D makes things so easy. Thanks to Gene and PropNut for putting me on to that one.
choowy - You're dead right, CNC parts make it as easy as screwing together flat-pack, perfect for people like me that have zero wookworking skills (you can instantly tell which bits I've had to cut myself because they look dog-eared compared to the ultra precision of the CNC cuts). But more importantly it saved me so much time.
Gene - The engraving bit I used was the starter bit that came with the CNC, it was a little blunt too after I'd taken an accidental bite out of some alu sheet with it. It looks to be around 30 degrees with a 3mm shank. I need to buy some more - what would you reccommend?
Here's some updates - the port skin is finally on and I couldn't resist a quick check to see if the 18.5" LCD fits (£45 ebay).
Clamping the skin:
Screwing around... (6mm head security pinned TORX self tapping screws - I only chose them because they had an interesting head pattern)
Perfect fit! Shame I'm going to take it to bits - I hope I don't break it...