The packs are usually good value if you compared to buying everything separately. Perhaps buy the sax and get the remainder on your Christmas list?
Having said that, the Bauhaus-Walstein (and a couple of others) shouldn't take all your £600 budget, so you'll still have cash left over to buy the rest of your goodies. Is it Tenor or Alto you have in mind?
That's a tough question with the info in your post.
You could land a quality sax for the extra ££ and if you have pocket money every month you get to choose your books and stand etc but.....
In order for that to become the best option you have to choose wisely all round.
There are a couple of Bauhaus walsteins (a highly regarded manufacture in this forum) in your budget with cash to spare!!!