when in 2017 was it registered, if before 1 april, the annual car tax would be £30, but after it's £145
if you don't know the date, tell us the reg no, and I should be able to find out for you.
also insist on a very long MOT especially if it is currently using an mot extension.
leaving cars standing for some time isn't good for them, the tyres can go 'square', brakes can lock on, battery discharge and modern fuel go stale.
but if it has been moved about a bit it should be fine.
surface rust on calipers and drums is normal.