re: entry level road bikes
The cheapest we’ve seen that looks like it might do the job and be fun to ride is the Decathlon B’Twin Sport 2 for £229. Decathon’s bikes tend to be good value for money and pretty well sorted. Evans do the Dawes Giro for the same money.
http://www.decathlon.co.uk/EN/sport-2-16v-42393911/
http://www.evanscycles.com/categories/complete-bikes/road-bikes?page=1
Going up a notch Specialized and Giant are two other brands that have always really punched their weight at the entry level delivering good bikes at excellent value for money. Expect to pay around £400 – £500 (the latter being closer to list). The Trek 1.2 at £450 looks pretty good too. At this time of the year it is also worth looking around for good deals on old stock.
You could also consider buying secondhand – your money goes a lot further then.