So it depends on your car or car charger.... if one or both is supported Intelligent octopus is hard to beat, 7.5p per kwh for 6hrs off peak (11:30pm-5:30am) and then a so so price for the rest of the day. its for the whole house as well so can benefit if you push your tumble dryer, dishwasher or immersion heater and what not to those times. Add to that you can also get extra bonus cheap slots if you car needs them to charge.
even more bonus if you have a house battery.
if your car or charge point are not supported then you are looking at octopus Go... which is 9.5p per kwh off peak for 4 hrs(12:30-4:30am) and no extra bonus times.
as said above, make sure you get a referral off someone as you will get £50 credit on your account, as will the fortunate person who referred you.