These are the PMR walkie talkie frequencies:
Channel Frequency in MHz
1 446.00625
2 446.01875
3 446.03125
4 446.04375
5 446.05625
6 446.06875
7 446.08125
8 446.09375
27/81 CB Frequencies
27/81 Chan. 01 .... 27.60125 MHz
27/81 Chan. 02 .... 27.61125 MHz
27/81 Chan. 03 .... 27.62125 MHz
27/81 Chan. 04 .... 27.63125 MHz
27/81 Chan. 05 .... 27.64125 MHz
27/81 Chan. 06 .... 27.65125 MHz
27/81 Chan. 07 .... 27.66125 MHz
27/81 Chan. 08 .... 27.67125 MHz
27/81 Chan. 09 .... 27.68125 MHz
27/81 Chan. 10 .... 27.69125 MHz
27/81 Chan. 11 .... 27.70125 MHz
27/81 Chan. 12 .... 27.71125 MHz
27/81 Chan. 13 .... 27.72125 MHz
27/81 Chan. 14 .... 27.73125 MHz
27/81 Chan. 15 .... 27.74125 MHz
27/81 Chan. 16 .... 27.75125 MHz
27/81 Chan. 17 .... 27.76125 MHz
27/81 Chan. 18 .... 27.77125 MHz
27/81 Chan. 19 .... 27.78125 MHz
27/81 Chan. 20 .... 27.79125 MHz
27/81 Chan. 21 .... 27.80125 MHz
27/81 Chan. 22 .... 27.81125 MHz
27/81 Chan. 23 .... 27.82125 MHz
27/81 Chan. 24 .... 27.83125 MHz
27/81 Chan. 25 .... 27.84125 MHz
27/81 Chan. 26 .... 27.85125 MHz
27/81 Chan. 27 .... 27.86125 MHz
27/81 Chan. 28 .... 27.87125 MHz
27/81 Chan. 29 .... 27.88125 MHz
27/81 Chan. 30 .... 27.89125 MHz
27/81 Chan. 31 .... 27.90125 MHz
27/81 Chan. 32 .... 27.91125 MHz
27/81 Chan. 33 .... 27.92125 MHz
27/81 Chan. 34 .... 27.93125 MHz
27/81 Chan. 35 .... 27.94125 MHz
27/81 Chan. 36 .... 27.95125 MHz
27/81 Chan. 37 .... 27.96125 MHz
27/81 Chan. 38 .... 27.97125 MHz
27/81 Chan. 39 .... 27.98125 MHz
27/81 Chan. 40 .... 27.99125 MHz
A couple of others:
166.075 Community patrol on AM
119.850 Liverpool approach
125.225 Valley Approach
The link below is quite useful for working out what you're listening to and finding the other side of the conversations where duplex radios are used.
http://www.wibble.co.uk/links/ukspectrum/spectrum.html