A quick whats where guide to scanning.

31 MHz & 32 MHz. Cordless phones
49-50mhz, baby monitors etc
70.500 - 71.500 MHz. Fire brigade.
PMR (Private Mobile Radio. i.e mainly business users.) 85.000 - 88 MHz.
117.9750 - 136.000 MHz Civil Air band.
138.000 - 141 MHz PMR
145.400 - 145.800 Simplex & repeater output part of the Amateur 2 meter FM band including International Space Station that is worth listening to.
156.000 - 162.5000 MHz Marine Band.
163.03125 - 165 MHz PMR.
165.0125 - 168.225 PMR
168.250 - 169.400 MHz PMR
169.843 - 173 - 0400 PMR
430.000 - 440.000 Amateur 70cm band. This band can be VERY quiet. But it is worth monitoring our local repeater.
440.0000 - 442.25625 mhz PMR
446 - 470 MHz PMR, including licence free PMR, Security, Shop & Pub Watch etc