already have a white GTI DSG on the drive that I got on a cheap lease (£107 a month).
Wait wait, only £107 a month?! Please share who that was with? 
This could be a good deal, it could be bad. It's almost pointless putting just your monthly figure in.
You need to take your monthly payment, multiply it by the number of months, then add the deposit, and then divide by the number of months, then we know how much you're really paying per month. Then you need to include your mile allowance.
He may have put down a £10000 deposit, be on 5000 miles per year for 5 years. Not such a great deal now. Obviously this probably isn't the case, and it may be a good deal, but we just don't know.