I tried both places to install the SSD (at the bottom and in the tray above) but both had the same problem, the screw holes on the case were slightly too high, meaning I couldn't secure the SSD in place. I have ordered a needle file, so when that arrives it should be a simple fix, by just filing out the bottom part of the screw holes and then screwing the SSD in place in the larger holes.
The install was straight forward apart from that. The most annoying part it probably trying to work out how to keep all the cables organised and out of the way as much as possible.
Thanks for all our help.