UK Postcode Validation

UK Postcodes do not seem to be validated properly. This is really important when setting shipping zones based on the postcode - for example: PO3 1AA PO30 1AA The important part is the code before the space - it designated the area. I can use PO3 * and PO30 ^ to signify the area in the zone - but if I enter the postcode without a space - for example PO31AA - the postcode does not register as being in a zone so no shipping is added! We need the UK postcode to be validated before the shipping is calculated - either adding a space before the last 3 characters - or just truncating the last 3