Thanks for the reply Andrew. I have decided that taking a chassis kit from HandyAndy would be my best option, it's a great price he's selling at considering how expensive steel is and the cost of equipment and time to cut it.
I have built my build table after flat planing many bent bits of scant and discovering quite how out of level my garage floor is.
So after many hours being quite particular I now have a perfectly flat and painted build table.
I started marking out but then stopped as I decided it would be easier to do when the steel has arrived although I did manage to get BR5, 6, 11, and 12 marked out and after checking diagonally I was maybe 0.6 mm out iirc! Which I thought was quite good.
I have spent most of the weekend either asleep or in the garage, that build table started to look very comfortable and inviting.
Oh also this weekend I managed to knock the passenger side wing mirror off of my donor by letting the build table fall on it!
Oooops!