lay off him i think if he wants VTS he can go ahead as long as he knows the costs, and if he does smash it, he will learn from it (hopefully not substaining injury to other parties or himself)
but seriously cat c VTS erm i would try and get rid of it and find another project by the sounds of it, its a dog and pointless running / insuring it esp for the money you'll be paying
i got VTR at 17 and as soon as i got 1years experience on the roads, i got rid of it for a VTS at 18 insured for £1600 full comp there are some good deals on insurance just got to keep a eye out but i do feel for you.... being on your own at 17 with VTS i wouldnt like to be you
there are options you can take such as
1) going under mum/dad name for the 1st year (i did that with the VTR and it helped alot saved me alot pennies)
2) putting the VTS in your mum/dads name and getting a 1.1 shitter or something and insuring that with bell which would allow u to drive the VTS on third party with the owners permission aka your mum/dad but the downside with this you'll be paying 2 sets of insurance, 2 sets of MOTs, 2sets of TAXs esp as being the VTS you have being abit of a dog i wouldnt bother and if you smash the S you'l have a complete loss it being cat c no point fixing it anyway.
3) the most sensible option as a few have said
your not wanting a slow as fuck car i understand how u feel

so i would recommend a VTR, best car overall and some quite good VTRs can be had for £1.5k or so now due to credit crunch
not completly slow, put a 421 on it and decat piper, sort brakes, slam it on springs and put good tyres on it you'll have loads of fun in it, returns quite good petrol, cheap insurance and tax
IMO a better all rounder than the VTS although the only real issue with the VTS is the insurance side of it which will be more sensible as you go along with road exp