Safety gear:
Helemts are dammed good nowadays. A £100 lid will do you as a weekend thing, but don't buy second hand. Generally I'd go Airi or Shoei depending on your head shape (you'll be one or the other). Look for ACU Gold and the BS label (I can never remember if green or blue is the better one, I think it's blue). The helmet shold be tight to put on but not pressure on your forehead or jaw, in this case chipmunk cheeks are a good sign. Also, put the helmet on and get a friend to hold the chin bar (I'm assuming a full face job here). If you can rotate your head inside the helmet it's too lose.
Next thing is gloves. The natural thing to do when you come off is to put your hands out, which will be bad news even at low speeds. Get a good pair, preferably double thickness leather on the palms and preferably no seams on the palms either. Budget around £30 for a reasonable pair.
For jackets, leaher's good but not waterproof, textiles are waterproof (ish) but expensive. Look for padding / armour in the shoulders, elbows and back. If you need a hanger to hang it up then you're probably looking in the right area. Budget around £150-£300 for a good jacket.
Jeans are important. A good set of leathers will set you back around £100-£150 and will have armour on the hips and knees. Don't bother with knee sliders, if you're good enough to do that sort of thing you won't be asking advise here, and if you're getting your knee down without experience I'm guessing the next bits will be hip, shoulder, head.... The alternative is textile trousers, which will be waterproof (ish again), and armoured in the same places. It's also worth looking for zips on the ankles so you can adjust them to be over or inside your boots.
You could go for an all in one suit, but they're much more expensive.
Boots, also very important. Things to look for here are ankle protection (think about a 400lb bike resting on your ankle), shin protection, felxibility in the ankle for dorsiflection and adjustment in the tightness of the boot upper. Also, work out if you're one of these people who like a flat sole or a normal one (I prefer normal ones, but there are those out there who prefer flat). Budget between £75 and £150 for a good set. Oh, and accept they won't be waterproof (no matter what the company says).
An all in one rain suit that will be waterproof and folds back into a small pack will be about £20. Personally I prefer a zip up the middle rather than a diagonal one that zips down a leg but that's just perference really.
The Bike:
For a first 600 bike, my reccomendation would be something that's designed for torque rather than all up power, and minimal fairing. While you're not guaranteed to throw it down the road, it's always a possiblity and the less fairing, the lower the repair cost. Honda are generally good (so a hornet or whatever they replaced the hornet with), the Bandit is an excellent bike but prone to corrosion issues, diversions were great (having a shaft helped them maintain a reputation with couriers) but an £800 bike is likely to need some attention. If it's got RR in the title it's likely to have been thrashed to hell and back, been down the road a few times and 'ridden like it was stolen'.

Other than that, learn to enjoy the ride rather than the race and you'll do just fine.