You would be mental to start off in a 335i.
With no driving experience you will also have to get used to costs involved in running a car.
Getting to 23 and not owning a car you will soon get a shock to find the cost of running an expensive car take a bit hit on your finances.
It does cost a fair amount to buy and run a 335i properly. Insurance won't be your only expensive bill to worry about.
There is good reason that the prices are what they are. Young men have by far the worst safety record for crashing.
£8000 pounds worth of damage is pretty easy to rack up with a reasonably minor accident.
What happens if you do have an accident? Are you comfortable with the thought of having to pay £3000?
For me that is far too much money to put at risk.
You should be able to find a bigger gap between a 335i and a smaller car. I've even noticed a few dealers offering good insurance deals when you buy a car.
It would be wise to get some proper driving experience and some no claims bonus before thinking about a 335i.