Some of the information I need is cut-off because the string is limited to 30 characters. Is it possible to obtain the full string? Or is there another source I could use to obtain it?
is there any way to obtain the full (non-truncated) string for the occstrng variable for the historic UK censuses?
Yes, this should be possible, at least to some extent. Complete (non-truncated or less truncated) occupation strings for the historic UK samples are available as source variables: UK1851a_OCC, UK1861A_OCC, UK1861B_OCC, etc. You can find these variables on the Source Variables tab of the OCCSTRING variable.