The creation of a hardstanding, ie tarmac over the front garden is exempt from the requirement to get planning permission (unless listed building or architectural conservation area) and therefore you will not be required to reinitate garden.
The vehicular access into the front garden requires planning permission, understandably given traffic hazard concerns.
It is statute-barred if the vehicular entrance has been in place for over seven years, unless there was a condition on the planning permission of a house, that no vehicular entrance be created.
You can seek retention permission for this whether it is statute barred (for peace of mind) or unauthorised.
The worse case scenario will mean you'd have to stop using it for parking. Generally councils will grant permission unless a traffic hazard is created.
Key considerations:
Is the vehicular entrance close to a corner?
Do the gates open inwards?
Is it a very busy road, can you turn in the front garden to allow you to always exist the site in a forward motion?
You should ask the current owner to bear cost of application and appeal.