Jason,
I ordered the same thing, but made sure it was under the £18 duty limit (postage doesn’t count), and they took about 14 days to get here, even though it was only a tiny package.
If you go above that £18 limit, then UPS automatically pay the duty for you (how kind) and charge you around £11 for the privilege, plus the customs charge, and won’t deliver until you have paid the excess. The post office do the same thing, but only have a surcharge of £8. You are always better off, if you can, using USPS, then you have a chance of, if it is not too far over the customs limit, getting away with it.
John