North congrats on getting the mtb bug, much fun ahead of you.
STW is a helpful site but some people will seem to know what you want more than you do, find a bike you like that feels right and buy it but do your research.
Sounds like the shop you went to was trying to upsell you, not uncommon but they were doing it with slightly odd advice, the FSR is a really good deal and currently you get 10% of Specialized accessories free when you buy a 2009 bike over £1000, worth bearing in mind.
If you can find a good 2008 bike in the right size I’d definitely snap it up as most companies have had to increase prices or downspec for 09.
From what you’re saying you seem to have the right idea, 120mmish full suspension from one of the big companies is a good choice.
But getting a bike that you like and is the right size is very important, shops are useful but some will push you into something you might not want and don’t pick up a bargain that’s the wrong size just because it’s good value.
As most people have said just get your leg over a few and you’ll find something you like.