Along with all their other Christmas items, B&Q have now reduced the price of real Christmas trees. They had some 4-5ft marked down to £1 and a variety of larger ones for £5. Mostly Nordman Firs left in my local.
I'm sure availability will vary from store to store, but there is still a reasonable range left in the Tonbridge branch.
Great excuse to ditch the plastic tree for a year and go for the real thing, should also keep the kids occupied for a few hours too.