Until January 2018 there were just eight frequencies for licence-free radios in the UK, ranging from 446.00625MHz to 446.09375MHz. After that, the frequency spectrum was expanded in line with Harmonised European Standards to create greater capacity across Europe.  

The extended frequencies now range from 446.0 to 446.2MHz, with a channel plan based on 6.25 kHz (for digital equipment) and 12.5 kHz (for analogue equipment) spacing.

Here's a table showing the whole spectrum of PMR446 frequencies, with the channel plan.

Analogue (12.5 kHz Channel Spacing) Digital dPMR446 (6.25kHz Channel Spacing)

Channel	Analogue (12.5 kHz Spacing)	Channel	Digital dPMR446 (6.25kHz Spacing)
CH1	446.00625MHz	CH1	446.003125MHz
CH2	446.01875MHz	CH2	446.009375MHz
CH3	446.03125MHz	CH3	446.015625MHz
CH4	446.04375MHz	CH4	446.021875MHz
CH5	446.05625MHz	CH5	446.028125MHz
CH6	446.06875MHz	CH6	446.034375MHz
CH7	446.08125MHz	CH7	446.040625MHz
CH8	446.09375MHz	CH8	446.046875MHz
CH9	446.10625MHz	CH9	446.053125MHz
CH10	446.11875MHz	CH10	446.059375MHz
CH11	446.13125MHz	CH11	446.065625MHz
CH12	446.14375MHz	CH12	446.071875MHz
CH13	446.15625MHz	CH13	446.078125MHz
CH14	446.16875MHz	CH14	446.084375MHz
CH15	446.18125MHz	CH15	446.090625MHz
CH16	446.19375MHz	CH16	446.096875Mhz
		CH17	446.103125MHz
		CH18	446.109375MHz
		CH19	446.115625MHz
		CH20	446.121875MHz
		CH21	446.128125MHz
		CH22	446.134375MHz
		CH23	446.140625MHz
		CH24	446.146875MHz
		CH25	446.153125MHz
		CH26	446.159375MHz
		CH27	446.165625MHz
		CH28	446.171875MHz
		CH29	446.178125MHz
		CH30	446.184373MHz
		CH31	446.190625MHz
		CH32	446.196875MHz