on top of the metacarpal is great! allows you to reach any reader with just a wrist bend. 
The forearm location, though, might get you dancing on the terminal.
In the UK some places have an acrylic sheet right by the side of the terminal, making so that your elbow gets in the way of trying to present the side of the wrist to it. Coop and Tesco Express seem particularly found of that layout…
Walletmor does not work in the UK.
They are still using iCard, and that company withdrew from the UK market after brexit.
Last I’ve checked, they (iCard) charge you £50 per month if your registered address is in the UK…
or a flat fee foreign transaction charge for every transaction you make in the UK if your address is registered anywhere in the EU.
The wording on their site is very dodgy, though, to the point of intentionally omitting the fact you would need to pay fees until after you purchased their services.