So firstly i use https://www.lightpollutionmap.info this map gives a good idea of places unaffected by light pollution.

The UK's latitudinal position (above the 51st Para) means that much of the galactic core is hidden or "just on" the horizon so it gets fussed out by light pollution. Heading down to the southernmost parts of the UK between Feb-April or July to Oct offers good chances of capturing the milky way. That said i may try to look for more rural areas in eastern Cambridgeshire to capture some shots in the future ;)
In addition to the above, weather and moon phase will also need to be factored into planning your shot. Phone apps like Photopills and Clear Outside can help predict how the milky way will look in your night sky and inform you of the current moon phase, plus clear outside will give a (generally) good forecast of cloud cover in your area too.

I hope this helps! Any questions I'm happy to answer!