You'd be better to try haggling for a reduction in price for not having a trade-in, then just get rid of your old one privately.
A car without an MoT is practically worthless and you'd be very unlikely to get even a sensible offer for it.
Lots of availability for �3000, nearly all hatchbacks and estates have fold-down seats. It really is just down to personal choice.
I have an Astra estate which suits me fine, but others have been known to pour scorn on my choice.
Good hunting.