Does Henry sell and mail his bags to customers outside the United Kingdom?

Yes. He can mail his bags to anywhere on the planet.
 

Is postage included in the price?

No. Postage is £8 ('next day') for almost all of the United Kingdom. Henry uses regular mail when posting abroad and postage prices abroad vary with weight and destination. Email Henry if you want to know the cost of a particular bag to a particular destination.
 

Does he ever use couriers (like FEDEX) when posting abroad to speed up the posting?

Yes, but by request only. It can be very expensive.
 

How can I tell how much a bag costs in a different currency?

Henry suggests the use of an internet currency converter like: http://oanda.com/convert/classic
 

How much more does it cost to have an existing design customised?

It depends on the degree of modification. Size change usually means making up new patterns which is expensive. Adding or taking away a feature is less expensive (or even cheaper). Specifying the length of the shoulder strap (a very common request) doesn't usually change the price at all.
 

How much do wholly customised bags cost?

Very rough guide only: about twice as much as you might have expected to pay if the bag already existed in his range. The exception is if he is interested in incorporating the design into his range anyway.
 

Am I able to return a purchase that does not meet my expectations?

Yes. If you are unhappy with your purchase (and you don't have to express a reason) you have ten days from receipt to decide to return it (unused) for an exchange or a full refund (except postage). Customised bags may be an exception.
 

Is it possible to see and feel the leather before committing myself to buying?

Yes. If you are a UK customer, you need to send Henry an SAE specifying the design and colour range that you are interested in. It will help if you include your email address and phone number in case he has any queries. For oversees customers, make your request by email/phone/fax.
 

Does the 28 day requested lead time mean that orders take the full 28 days before delivery?

No. 28 days is a maximum. Most orders are fulfulled well before and requests for a quicker turnaround time (Christmas/birthdays) can usually be accommodated.