Hi - I just had to post recommending Interparcel
It was the first time I'd booked a courier and I must say I am very impressed.
I was sending a car seat - when all parcelled up it was bigger than most couriers' economy services so I was being quoted a fortune (£30 - £50 odd). However my parcel still qualified for their economy service cost £10, straightforward booking on-line. Would have been delivered withing 24 hours but buyer was out so re-delivered the day after, no probs.
Just wanted to share