I generally ship items with Royal Mail, Royal Mail have many shipping options available, I usually offer the following:
Tracked 48 which costs £2.85 and usually delivers in 2-3 days after disptach
Tracked 24 which costs £3.95 and usually delivers next day after dispatch
While I do try to ensure items are sent out quickly, I am not at liberty to give any guaranteed dispatch timeframe and Royal Mail's delivery estimates are only estimates, please do not contact me about items taking longer until it has been at least a week past the expected delivery time.
orders from outside the UK are usually also shipped with Royal Mail, international shipping is less reliable so I would recommend choosing International Tracked and Signed, especially if your destination country is not on this list:
These above are the countries I have had good experiences shipping to.
While Royal Mail claim that items should arrive in 3-5 working days for shipping to Europe and 6-7 days for worldwide shipments, I think these are rather optimistic based on experience, different countries have different customs services which can be known to hold items up for a while.