If you fancy it you should really try it. I've probably done 15ish track days although not done one for about 3 or 4 years now and i've really got the itch to start them again but i need to get a cheap car to start doing them again.
The best advise i can give is don't turn up to a track day with road tyres and road brakes, flush your brake fluid with some good quality high temp stuff and get some better front brake pads. Even stuff like the EBC yellowstuff are ok to start out with, then ideally get some racier tyres as road ones tend to melt after a couple of laps and it's just no fun at all especially on a heavier car like yours.
Then listen to the briefing and just take it at your own pace and build up through the day, if someone comes up behind you let them past and it'll be fine. In my experience the fastest thing on any track day you go to will be a tatty looking Clio which will be hooning round passing everything, you really don't need a fast or expensive car to have fun or be 'worthy' of taking it to a track
Have a look if your local track has any clubs you can join, my local one has one and they run maybe 5 or 6 evening sessions for club members through the summer. They usually run from 6-8pm in 20 minute sessions (novice and experienced) and it was quite cheap, they started at £30 for the evening but i think they're now around £50. I found 1 hour of driving (3x 20min sessions) was enough for me as i didn't get tired and start making mistakes and you didn't totally trash your car for hours.
You will go through fuel very quickly though, my old Subaru would do around 28-29mpg on the road but i was getting about 11mpg on track, i think about 70-80 miles from a full tank which was about an hour of actual track driving so if you do a full day somewhere that can really add up. For brakes and tyres it really depends on your car, when i settled on some brake pads i liked i could get quite a lot of sessions out of them so maybe 3 or 4 full days worth and tyres again depended on how you were driving but could easily do 3 or 4 days.
Once you've done a couple then you'll probably want to look at mods but i'd for a few in the stock car first, then you'll probably want to strip it out more and have some coilovers fitted. You can then just have fun and enjoy it or go mental and turn it in to a track weapon! All i had on my car was better aftermarket brake pads, discs and brake lines and some coilovers, i always though any mod i was thinking about could be spent on more track time instead which was far more fun!
Edit: - Oh yeah, the best thing i actually did to the car for track stuff was getting some racing harnesses as you really do slide out of your seat with the standard seat belt so that'd be mod 1 for me after you do your first day!
had the track to myself, car wasn't over heating, i could stay out for 10 laps at a time 
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