You won’t get a decent delivery for much less then 5.99. We have accounts with DPD and Parcelforce, they’re £4 to £5 plus VAT, I’ll double check the rates on Monday when I’m in the office, and check price for third party collections too.
I have also used parcel monkey and parcel2go to get quotes online, they show all the options available. You usually need parcel weights and dimensions
I wouldn’t consider Hermes or yodel