Costco have the Stanley SPK laser level + tripod
for £19.97+VAT (i.e. £23.47) for those with access to a card.

It's this one which screwfix have for £40
http://www.screwfix.com/app/sfd/cat/pro.jsp;jsessionid=BEMVD23BBL31MCSTHZOCFGA?cId=102095&ts=21432&id=50951