You've received plenty of comments and suggestions, most of which I concur with.
I don't know how new you are to the hobby, so forgive me if this comment is off…
It's worth the effort to learn a few basic nib adjusting tricks. It's not uncommon for tines to get out of alignment after using a pen for several years (especially if you ever let someone borrow the pen). I won't do anything too crazy, but a basic smoothing, tine alignment, and making a pen wetter are all very easy, even for a beginner. There are some good YouTube videos showing how to do each of these things.
If you don't feel comfortable starting on an M800 (understandable), practice on a cheaper pen. As long as you go slowly you're not likely to cause any permanent damage.
I've had to adjust a handful of pens (even an M800) and have yet to damage any (and this type of thing is not in my normal skillset; I'm as handy as a bike rack). I've also had a couple pens that needed more work than I felt comfortable with and sent those to a nibmeister (e.g., the tines on my M1000 were visibly misaligned when I received it).
Also, generally you get what you pay for. £300 is a fair deal for an M800 but still well below many retailers. You'll pay more for the same pen at nibs.com or nibsmith.com (or other shops with in-house nibmeisters) but they'll generally adjust the pen for free when you order.