Paul,
Sounds like you have a decent amount of space to put up a decent sized antenna.
I ask the size as I was looking at a Broadband Butterfly Dipole that I noticed on Youtube.
https://www.youtube.com/watch?feature=share&v=Y473hOmif-E&app=desktop
Not sure if it is something you could try out but worth considering if it is a stealthy optiin you need to stick to.
If you haven't yet bought a radio, might it be worth you looking at a small SDR device that will plug into your Laptop / PC if you have one?, couple that with an inexpensive antenna and it should give you an idea of what is available to you.
They are fairly inexpensive and would give you an idea of what you are capable of receiving before you outlay more money on something that may not work for you at the moment?
Regards
Graeme.