New rules linked to new tariffs and customs procedures risks increasing the administrative burden for many companies, especially those not used to trading with countries outside of the EU (please see below for more information "We have very limited experience of handling customs procedures. Can we hire someone to do it for us?").
In the longer term, limitations following the UK's new regulatory independence may pose problems for companies. For instance, we risk seeing changes in jurisdiction on intellectual property, GDPR, competition law, disputes and arbitration as well as potential non-tariff barriers due to diverging regulation and requirements of multiple different standards (CE-mark, etc.)
Further, just as required when trading with any other country outside of the EU, a no-deal Brexit will require Swedish companies to have EORI-numbers in order to export goods to the UK. This can be applied for at the Swedish customs.
Finally, as a company you should make sure you still meet the requirements of other free trade agreements. Leaving the EU implies that all goods from the UK, previously having preferential origin in the EU, will lose that status. Hence, your product will also lose its preferential status if it is dependent upon goods from the UK having EU origin status in order to fulfil the rules of origin. This can be applicable in trade with other countries to which you might sell today.