I think we will be ok. as long as we make the right decisions in the process.
It may seem a bad idea to also leave the free access to the common market but I disagree because we can charge an import tax as well as the EU. We import more than we export so we will make more money than we loose. Companies will avoid the importation duty tax by building sister factories inside the UK and that will create more Jobs.
When we get trade deals with other countries such as China, we can ensure the deal is selective so we only remove the tariff for products we don't produce or need on the cheap such as Olives, Rice, Avocadoes and Medical commodities such as Oxygen Masks, Bandages, and Drips. So our companies don't face excess competition. In return, we can sell our processed food and services back to them. If we were inside the EU we could never get such a deal and would have to settle for the best-fit trade deals for the whole Union.
The money we pay into the EU will be ours to spend on projects that we need,