I don't know whether US Customs allows you to declare "Goods to follow" for your personal exemption and how that applies to goods that might otherwise be subject to tariffs.
I don't know whether the tariffs has resulted in greater inspection and assessment of goods brought in by travellers and returning citizens.
Normally I would assume that shipments entering the UK would be subject to UK taxes on import.
https://www.gov.uk/import-goods-into-uk
I don't know if the UK Customs services at the points of exit will refund VAT paid on import (of parcels) as they might for UK goods bought for export.
I know if you ship to Canada you pay the tax plus fee on import, but can claim a refund if the goods are reexported. I don't think the fee is refundable though.

Regards

Mike C

The following is based on my personal experience over the last five years, others may have encountered different issues;

Generally the dealers will remove VAT prior to sending, but there are dealers in Germany who will not ship to UK so you need to check. If you are buying from Greece they are not allowed to deduct the VAT and so you risk paying twice, and Switzerland have their own rules and some dealers are cooperative others are not. But the main dealers in Germany will deduct VAT as will a lot of other dealers throughout Europe.

For the items that I have shipped to the UK first there is a limit of UK Pounds 100 that allows the item to be imported as tax free, this includes business related items such as samples and such. There is also an upper limit of Euros 1000 whereafter the package is not considered a personal import and requires a formal tax declaration and is assessed in more detail by Customs and Excise. They look at what is being imported, are they antiques or high value items and sometimes open the packages and will ask questions about content such as reason for import etc. Some companies will charge for this additional customs declaration and I have paid up to Euros 50 for this in the past

Assuming your package is over 100 UK pounds and below 1000Euros, the package will either be shipped by courier or by post, the package is subjected to the customs and considered a personal import and the item will be assessed for tax (usually just VAT on model railway stuff) and you are asked to pay the tax plus a handling fee usually around UK pounds 12 (but can be more) before the package will be delivered to you. I have checked and usually the tax is between 20 - 22% of the value. I am not sure why it varies but the process for challenging the tax in the UK is complex and painfully slow and so assuming a Euros 360 loco the difference is Euros 7.20 it is not worth my time to raise a challenge and then wait for a response.

Please note the following;

1) Royal Mail - all items arriving by Royal Mail now receive a tax notification by post and email which can be paid online anywhere in the world.
2) Parcelforce - up until June 2025 (last time I received by Parcelforce) they send their tax bills out by post, so someone has to be present at the address to receive this tax bill and deal with it, can be paid online but is pain in the ass. I have found it easier to do over the phone.
3) FedEx and DHL Courier - tax notifications are issued by email and can be paid online anywhere in world
4) DPD (a courier company) - if you item is sent by this company you have a 70% chance you may never see your item full stop. They are a disaster with NO customer support. My last package was delivered to the wrong address then returned to Denmark and to date I have still be unable to recover the tax I paid. Avoid at all cost.
5) Please note German DHL is generally not a courier service but post service, so if sent in Germany via DHL it will arrive in UK via Royal Mail or Parcelforce. If you want DHL courier you need to ask specifically for this.

Finally, as stated above it is possible to import items as samples (this generally works as a one off) especially if you are visiting from US and there is a statement to the effect it is a sample for business purposes and they enclose an invoice with the nominal issue the item may enter tax free. I have done this once, and I had no issue.

Please note that the tax system there is an anomaly I have found in that the tax is based upon the invoiced value, so Modelbahnshop Lippe offer a discount system which I save on my regular orders so once a year I have an order that I use my discount and this year, I had an order worth over 400 Euros which is discounted down to Euros 40, the customs only recognize the Euros 40 value and there is no import duty. So if you have credits which such companies this is also a good way to save tax.

Oh and if you are lucky the tax man misses the odd package so this year I think I had 2 or 3 that have been delivered with tax being applied and I have no reasons why.

I hope the above is helpful.

Best Regards

Glenn