Any 5w40 API SL good quality oil will do; Halfords do a nice synthetic 5w40, again made by Comma (allegedly).
You could try these people Opie Oils as they offer a club discount plus extra discounts from time to time. Don't discount using your local parts supplier as they often sell Comma oils at a lower price than Halfords own brand.
Oil is a religion & as such there are so many opinions on what is best but consider this: as most people do little mileage & treat their car better than the average then a yearly oil/filter change with a good quality API SL 5w40 will more than suffice.