Hi
Go for a 5w-40 synthetic and you will find those through the link below.
http://www.opieoils.co.uk/c-656-5w-40.aspx
Out of those, the best ones are the Silkolene Pro S, Motul 300V, Redline and Gulf Competition. The Motul 8100 X-Cess, Gulf Formula G, Fuchs Supersyn and Mobil Synt S are good, cheaper alternatives.
As a budget choice, a 10w-40 will be fine and I would either go for the Fuchs XTR or Motul 6100
http://www.opieoils.co.uk/c-657-10w-40.aspx