The trickle charger you (should) get along with your car as part of the deal. They plug into a 13A socket so you don't need a wall box or anything fancy, but they do take a long time to charge a car. For example my car was on 41% when I started it about 10 pm one evening, and finished about 2.30 pm the following afternoon. Over 16 hours.
They're useful if you don't do a big mileage - if you're only doing short journeys most of the time you can pick up what you need overnight fairly easily. If you have a convenient rapid charger for occasional use that may be all you need.
On the other hand it's not really practical to use them with variable electricity tariffs because the low-tariff period in the middle of the night probably isn't long enough for you, and you also have to be careful with electrical safety. Best used from a robust power point on a separate fused circuit. Watch out for the plug heating, and again best if this is in a cool area to allow any heat to dissipate. Extension leads can also be problematic. If you need an extension lead this has to be heavy duty, and again heating up of plugs can be an issue.
Having said all that, I have a separate electrical circuit in my garage with its own circuit breaker, the garage power points are all metal-jacketed, and there is a power point only 1.5 metres from my car's charging port so I don't need an extension lead (the granny charger lead is only 5 metres in total). It's also a dark, cool space. The electrician says it's all as safe as anything else in the house (nobody is ever going to say that anything is "perfectly" safe).
I also have a rapid charger five minutes walk away which is currently 2.9 p per unit cheaper than my own electricity supply, so I have a habit of giving the car a wee while on that to take it up to 90% or 95%, then finish the charge slowly on the granny charger which allows the battery cells to balance.
Last night I came home at ten at 30% charge. I gave the car 55 minutes on the rapid charger, took it home at 89%, plugged it in at home at eleven, and the app said it would be done by 2.17 am. I presume it was - it's at 100% now, so it only spent three and a bit hours on the granny charger.
I find this works very well for me, although it probably wouldn't suit someone with a high daily mileage. I'm certainly struggling to justify shelling out £1,000 for a wall box.
