Car insurance question

[Justvisitingthisplanet]

I just did my car insurance renewal on-line. I changed policy provider to save £200. I just realised the start date is 1 day too early ie the old policy and new policy overlap by 1day.
Do I need to get that changed? Will I end up paying admin fee to do that?

I would just leave it tbh.

Leave it. If you have a shunt on the one day that you have double cover the insurance companies will share the expense.