It is always useful to check the ownership or leasehold of any site to compare what the parking company claims with the reality at the Land Registry. The parking companies sometimes forget the contract they have has been cancelled by a change of ownership. Or even that they never had a contract in the first place.
Access via the Gov UK site
There is a link (here) on the Gov.uk webiste that takes you to the Land Registry section so you can carry out any property searches you need.
Search using the Postcode
The search is best by postcode but you will need an accurate postcode to find the property - unless it is your own!. There is a help desk at Land Registry if you get stuck.
See what is available
There are usually two types of title you are searching for, the Freehold and the Leasehold. Best to get both for the sake of clarity as these documents can refer to each other.
Purchase the items you need
Purchase both the Title Register and the Title Plan. The first should give you all the rights and restrictions. The second covers the space/area that is covered by those rights and restrictions. You will need to create an account with Land Registry but it disappears again after about a year.