BundleBox is a good service to become acquainted with, because not only does it offer a complete US redirect service (including taking care of tax and import charges) but the company will even buy a device for you if you're having difficulty paying for it on your credit card. They aren't currently taking any more iPad orders though, although they will start again on 21 April 2020 at 10:00 AM. Mind you, you'll be lucky to buy one before then now at any rate because it appears that most places have sold out.
If you can secure an iPad outside of BundleBox, you can still use its service to redirect the iPad to the UK. At the moment it is quoting £104.18 for a complete tax, import duty and shipping service from the USA to the UK. The basic iPad is $500 although you may end up paying US tax, plus a recycle fee, and expedited shipping charge bringing the total in the US to $563. Take the US amount converted to sterling and the UK amount and you're looking at around £468 to get an iPad into the UK (you may also have to pay bank charges for making an overseas payment).
At the moment the going rate for an iPad on eBay using Buy It Now seems to be around £590, although it was £500 before the delay. Some US sellers also seem to be offering iPads and international shipping, so you'll probably get a better deal from a US seller that does international deliveries on eBay.com.
Personally, we advise people just to wait. Unless you are a developer with a vested business interest in securing an iPad as soon as possible, it's probably better to hang on for another month than go through the hassle of trying to get one on import from America. Especially if you don't have friends in America to help you out. By the time Apple has started delivering to the US, and sent it to the US address, and then shipped it over to you, it'll only be a couple of weeks before you can get one in the UK.
If you are determined to get one now as soon as possible, we'd take a look at BundleBox on the 21 April and see what they have to say, or pick one up from eBay, but be prepared to pay over the odds.
If anybody else has any further advice feel free to pass it on in the comments section. Please note that we do not allow any personal sales listed in our comments section and we do not endorse any companies or services that any of our readers suggest. You spend your money on the internet at your own risk. If somebody offers you an iPad in a personal sale we advise you to pay cash and pick up in person.