Yes, it'll be heavy (though 15kg isn't ridiculous) and it won't be much good in the Tour de France but if you're after a simple, cheap bike and can do some basic assembly and setup this will be much better than your average supermarked BSO with pointless suspension, etc. You also have Halfords to complain to if necessary with a better chance of being understood and helped.
Personally I'd spend a little bit more on a simple bike but if this is all your budget will stretch to it's about as good as it gets.
Assembly costs extra so you'll need to do some basic stuff yourself (there's a helpful video on the link though it does seem to be a bit over the top for a very basic bike).
Happy New Year!