I found with kitchens you need to look at the whole price, as some places do cheaper units but the integrated stuff was very expensive, and most places hammer you for worktops.
Personally, I got quotes from Howdens (OK quality, not great, but not bad but very easy to fit), Magnet (expensive!), Wickes (not great quality), John Lewis (mental prices) and a local kitchen shop.
John Lewis units were the best I saw, but the price was stupid so after a bit of digging I found out that Mereway make most of the units for John Lewis so I tracked down a local kitchen shop who stocked Mereway and looked at what they had, as they were ~ 1/3 of the JL price.
Quality of the Mereway units was much better than Howdens/Magnet/Ikea and Wickes so I went with them.
Got the units from kitchen shop, appliances were on offer in a local department store (Rangemaster Cooker + Dishwasher) and got the Belfast sink (Shaws) electrics (lights etc) from Caple which are a much better quality than the stuff you get from screwfix etc. Worktop was from worktop express and is OK, and took them 3 goes to get to me undamaged which was a pain in the arse.
Not sure if I would pick a wooden worktop again, as whilst they look good mine buckled under the dishwasher even after 8 coats of oil and a heat shield.