
Is there anywhere else you could advertise the car? If it's not worth much, then it's not worth spending loads to keep advertising it in expensive magazines.
How about a bulk e-mail to all your mates to see if a friend-of-a-friend is looking for something? Tried eBay or similar online auction sites? Use your imagination... or check out your local car auctions. Selling your car at auction, with no reserve if it's a bit of a banger, is relatively cheap and hassle-free, with little likelihood of any comeback if you've described it honestly, even if you don't get a lot for it. Take the money and run. You don't want to keep the car, after all.
Complete the paperwork
Sign and send off each relevant part of the V5 (log book), with the date of sale on it - you don't want to be held liable for any parking tickets, speeding penalties or other motoring offences the next owner might rack up. Then relax, count your money and enjoy your new car.