Neighbour has blocked access to car park

[Jaba23]

I shared a gate with my neighbour in our terrace to access our car parking area. Each of the houses in the terrace of four owns a car parking spaces adjacent to our gardens. My use of the gate shared by me and my immediate neighbour meant me crossing 30cms of that neighbour's garden. This arrangement has existed for about 17 years when the current garden/parking area configuration was created by an adjoining development being built. When I bought my property 13 years back my solicitor did flag up that no RoW was currently on my title (titles only registered in 2002 as individual plots in the terrace) but I was in a hurry to complete so didn't address this then (dumb, never do this!). My neighbour has now built a fence that does not include a gate so I can no longer access my parking space without a 5 min detour along a public road. I have tried to resolve this with the neighbour as i believe if we can reach an agreement (she currently uses a bit of my land to access her car parking space) we can just register with the Land Reg. The previous owner of my property used the shared gate which means that it has been used for over 20 years but not by the same occupants. Can that combined usage constitute an easement? Any advice please?

Agree, not straightforward and I am grateful for all your guidance. The access path to parking is on my deeds as a consequence of sloppy conveyancing I think or the developer didn't want to maintain it or be liable for injury . The path and parking area were only constructed around 2005 (I am attempting to find out exactly when) when the new development was built. Ditto the previously shared gate with OP. I think the four houses in the terrace probably didn't have access to the rear as there were no parking spaces - it was undeveloped land. So in fact the 20 year easement rule apply to neither of us currently. But obviously I would like the previous access to my parking space back as currently I am climbing over a back railing to avoid using the road late at night or if I am in a hurry. I have told my neighbour that if I injure myself doing that I will sue her. Probably not very emollient, but it is a tricky manoeuvre....

I have told my neighbour that if I injure myself doing that I will sue her.

on what grounds?