'Interactive' maps of Pembrokeshire are available from this page. Please note that if you were using the old mapping system to find addresses by their exact location (rather than the nominal postcode location), we will not be able to make this service available due to licensing restrictions.
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 software can be found here https://www.gislounge.com/free-gis-data-viewers/ or http://gisgeography.com/free-gis-software/. 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).