Mamya's link assumes that the land hasn't been registered but it might have been.
Try searching from here:
https://eservices.landregistry.gov.uk/eservices/FindAProperty/view/QuickEnquiryInit.do
Start by clicking on 'Map Enquiry'
Then enter the name of the street and the town before clicking 'Search'. (You can leave the other fields blank).
Then follow the instructions to move around the map, looking for the land that you're interested.
When you've found it, zoom into it and then turn 'Find Properties' on.
If the land is registered you should then be able to download a copy of the title deed for £3. (There's a registration process to go through but it's very straightforward).
That search facility works for all registered land, irrespective of whether or not there are any houses (or other buildings) on it.