The Yamaha Pacifica is apparently a highly recommended first-time guitar - I've never played one mind. Apparently they retail in the £200-300 region.|
When learning, the most important advice is to practice regularly and often, even if you don't spend long at it each time. Playing for 15-20 minutes a day is worth far more than spending two hours every couple of weeks, particularly early on when your fingers won't have the strength to be able to play for longer anyway.
And also, progress is never steady - it won't seem like you're getting better every time you play and sometimes it can feel like weeks or even months have gone by without you improving much, but you will be getting better, and one day you'll suddenly realise you can play that riff or solo you've been struggling with for so long, and that feeling is impossible to beat.
I can highly recommend those book and CD 'Learn the guitar' packs you can get - I've been through a number of them and whilst the quality does vary a bit, I've learnt something from them all. Reason being, I think, because the most important thing with the guitar is to just keep playing. Realise you can spend a lifetime playing and still be improving and you'll get on fine - expect to be a blues legend after a week and you'll fail.
Edit: Regarding the advice on getting a tuner - I'd say get one and keep it as backup, but try to tune by ear before resorting to using it. Tuning your guitar by ear is vital to developing your musical ear and use of a tuner just encourages laziness on that front.