Geographic data produced by Pembrokeshire County Council is available via WMS and WFS services using this URL - http://inspire.pembrokeshire.gov.uk/services/wms. You will need GIS software to use these services, QGIS (http://www.qgis.org/) is a free, fully featured desktop GIS application.
Other GIS data viewers can be found from here https://www.gislounge.com/free-gis-data-viewers/.
Background mapping to use with the data is included in Ordnance Survey's free OpenData offering. Alternative WMS background mapping services are available (the QGIS plugin 'QuickMapServices' allows easy loading of some of these, or see the documentation of your preferred GIS software).