If you can imagin yourself going to your first race, being accidentally punted off the track in lap 3 and converting your former vehicle to metal shreds within 10 seconds, then crawling out of the debris and saying "That was worth the 7000£!" you're good to go.
What I'm trying to say is: Just make very sure your expectations are realistic. Your car will fail, you will have to make repairs from car-to-car contact, you will not make it to every race and your funds will not be enough by any means.
If you're still enthusiastic, and I'd be if I were in your position, you're good to go.
I think you'd regret it if you don't do it.
...Though perhaps I'd go for rallying, but that's personal preference.
Vain