We're not in the UK so I don't know if a comparable service exists for you lot, but we had a guy round recently to do an 'eco audit' of our energy use. He concluded we weren't doing badly for a family of 4, but gave us a list of renewable electricity suppliers (we chose Greenpeace Energy in the end, which is great because any profits are ploughing into their campaigning) and recommended swapping gradually to LED lightbulbs because they're more efficient than the 'old' low energy ones.
Apart from that:
I work from home so no commuting, and DH goes by bike and train. We have a single car which gets used about twice a week for shopping etc.
I've long had a mooncup, but will now be combining it with period pants and washable pads.
We compost and recycle to the extent that we have our weekly rubbish down to 60 litres. Our aim is tickt food waste to zero, and we're not far off that.
I've started sewing and love repurposing old clothing and fabric, eg currently making a rag rug from strips of old clothes.
Everyone has a weak point, and for us it's flights. We live in a different country to our families, and DD1 is somewhere else again, so flying to visit people is way more than a frivolous holiday. Even so, it's not more than 6 times a year or so, mostly short haul.
In the Long Term we need to get our roof redone, which will reduce our heating bills hugely.