Hi Simon, welcome to the forum!
Had the flat pack chassis kits been avaliable when I started my build I think I may have gone for it. I ended up hacksawing and grinding all my tubes to length on a wonky 'workmate' on the front (sloping) drive - not the easiest way to do it! I'd go for one of HandyAndys kits
Where abouts in Surrey are you? If your close to Bromley your welcome to come round and have a look at my build, may help with understanding how it all goes together. Also before I started my build I mocked up the basic chassis on CAD, I'd recommend it as it helped me get the build process settled in my head.
Cheers
Josh