Do you rent from the council and is the area in front of your house owned by them?
I apologise for the delay in replying my computer is slow today and I had to turn it off for a bit.
The garage would have prevented you from parking in that space and you have , presumably, not had use of that area so possessary title does not arise.
As such, you are no worse off than you were before and the access to your property is not affected anymore than previously.
I understand your annoyance but I am afraid there is nothing you can do here.
Sorry for being the messenger of doom
Does the proposed parking space remove any footpath so you go out of your garden directly into the parking space are?. From the plan you supplied there appears to be a footpath.
Unfortunately, there is no right against being overlooked probably because we are a small crowded island and such a right is not practical or enforceable.
Renting the garage would not give you any rights in respect of it.
I am afraid so, you only own the extent of your property