Using experienced partners both here in the UK and the country or countries you are looking to expand into is crucial. For example, working with both a UK accountant and an accountant that is familiar with local tax and accountancy legislation is crucial.
It may be worth considering banking with a financial institution that operate both here in the UK and in the chosen country you are expanding to. Not only can you profit from their experience, but the bank may be able to do some additional due diligence and offer you advice about the local business environment. They may also be able to secure funding for your expansion.