Ooh we've done this: UK to USA and now coming back in a couple of weeks
A few things to add to all the helpful posts you've already got:
(Also this applies to USA so Canada might be different)
Hopefully your relocation package will give you a lump sum - but with us they only pay for transport of goods up to 5k and we have to provide receipts - so can't just take the money and buy new furniture with it etc.
We are going with John Mason's this time and it's costing £3700, but we're not shipping much furniture - only one room's worth, the rest is just household items (about 300 cubic feet)
Don't bother shipping anything electrical - unless it's dual voltage it won't work over there (USA at least)
The wiki expat forums are very very useful!
Beds are different dimensions so we didn't ship any bedding. Even The exact same Ikea cot we own has different dimensions in UK and USA!
We paid for an extra bag when flying so could take as much as possible with us, and this time we will be sending a couple of boxes of things we may need via UPS/FedEx (air) so will be there just after we arrive - just takes a couple of days.
Not having credit history is a total pain, and the Amex tip didn't work for us. We had to borrow money from my mum to be able to buy a car as couldn't get one on finance. We took out secured credit cards at first to built credit history. There are many blogs online about other ways to build it up. Finally got a good rating after 2 years and now we are leaving 😂
Wetransfer is a great cheap service for moving money, and they've just launched an international bank account that is way cheaper than any of The major banks
Hmm there's probably lots more! But you have plenty of time to prepare, we only had a month or so and managed, so you will be fine
Good luck!!