Had a quick look on Google but August appears to be the most recent issue there's anything on line about although I don't know if they have a forum of their own. Otherwise the only thing I can suggest as it's the current edition you could nip into W. H. Smith and try not to look to furtive while you read the article. Alternatively you might have to buy a copy. Essentially the writer came up with 3 different upgrade packages varying in cost starting with wheels, tyres, seat, pedals and brake blocks which he thought made the most startling difference, especially the wheels and tyres. This cost him £327. The second upgrade package consisted of yet better wheels and tyres, new calipers (and brake blocks) different saddle and pedals this time costing £567. The third package was purely personal alterations such as (another) different seat, iPhone cover,mudguards, saddle bag, stem, frame protector, bottle cage and bar tape. I think he tried to change items that could have been done individually rather than large scale changes such as gears, the thinking being that if you wanted a 27 speed bike you'd have spent the extra on one in the first place rather than changing the cassette and whatever else was needed.
Anyway, tomorrow's Saturday so while the other half's in Tescos doing the shopping you can hang around the magazines and have a quick read