Finding Digital Surface Models by area (if they exist for the relevant region) on the UK government website isn't too difficult https://environment.data.gov.uk/ds/survey/index.jsp#/survey

The creator uploaded the convert-to-3D program, so once you've found the files it should be possible to turn them into 3D files provide you're comfortable running stuff from the command line and following his advice on parameters. https://github.com/andrewgodwin/lidartile

I haven't tried it yet though - it's on the to do list!