My experience with US stuff coming via Parcelforce once in the UK is they cock it up entirely and eventually send it back to the US.
With US orders, always if you can, avoid any courier option that will result in Parcelforce doing the UK part.
Couriers will automatically charge you for duty and a huge handling fee, regardless of what Mount Pleasant decides, sometimes sending an invoice weeks after delivery.
Any option that will be dealt with my standard Royal Mail in the UK stands a better chance of not being charged at all and more likely to get to you, plus the handling fee if they charge is sometimes less than some of the couriers.
Small items I used to order from US, I’d pick anything that went via Standard/airmail USPS as it wouldn’t be handled by couriers. Avoid express options as that will trigger Parcelforce.