Hi JimF (and thanks to John Ackers)
The problem with engaging companies to provide cycle parking is that, not surprisingly, they tend only to recommend and install products which they themselves supply. That's not to say that they won't do a good job, but you almost certainly won't have the fullest picture of what's possible.
You don't necessarily need a specialist installer, in fact. Given the right instructions and supervision, the installation work can often be done by any competent handyperson. Your management company no doubt employs people to do general maintenance and installation work. Worth asking them if they would do the work, if provided with a layout diagram.
Sheffield stands are an excellent and economical solution, in the right circumstances. And they are available to buy cheaply from loads of different suppliers (Broxap is a good one).
Check out the last two pages of this PDF...
...for some useful diagrams showing recommended spacing, which is VERY important.
But I would need more details to comment sensibly on the details of what you are planning -- things like dimensions, whether or not the location you have in mind is covered and locked, and what material the ground/floor is made of.
Feel free to give me a ring on 020 7729 2273 or email firstname.lastname@example.org to run through your plans.
London Cycling Campaign in Hackney