If you can afford it, get Altium. Or a student edition or something. PCB manufacturers will take pcbDoc files straight from this. Same with Eagle though as well. Not sure about DesignSpark to be honest, if PCB places use those files directly. Best to ask them, or ask them how to make Gerber files from DesignSpark.
I recently made a panelized design, for design for manufacture. I did not do anything "Special" in terms of placement, just my usual layout techniques and dont clutter your components up too close (leave 1mm or so at the very least! between small passive components like resistors).
The issue I ran into with Altium was my schematic symbols "Comment" fields did not have the exact manufacturer part number from my Bill of Materials on them, so when the PCB assembly guys went to program the Pick and Place machine, the components on the PCBDOC file didn't have nice comment fields as they had expected (nobody told me this, i learned the hard way). Instead I had made a component designator -> manufacturer part number assignment spreadsheet in Microsoft excel which they ended up using to work out what parts went where on the board file.
Altium component positions and orientations are pulled directly out of the file and used for pick and place machine programming. I suspect other PCB CAD programs can generate pick and place files too, but I only know of Altium's capability.
I also made a separate board file and deleted all the components that I did not want loaded, and made PDF documents showing the top and bottom side component layouts in a really nice and obvious fashion for the manufacturers to see what I actually wanted loaded. My design had a lot of extra functionality that I only needed on 10 out of 120 boards, that is why I had spare pads..
I hope this helps?