Would it be a good idea to get a mentor to help me in my plans?

Yes, your main focus should be on the core business. Everything else to do with tax, licensing and so on you can get help with. It is a good idea anyway to get yourself a trusted accountant who will know many of the answers to the questions in this FAQ. You may also find mentors for free for example from Egen Virksomhed Nu, from the local Business Club or the local government business service. 

More information
Most people who start a business do not know much about the legal and financial side. It is a good idea to connect yourself with someone that you trust who can help you with all these aspects. You can do this for free by having a mentor who will help you at the beginning. For example, http://egenvirksomhed.nu  You should also consider paying an accountant to take care of all your administrative and financial work. You would pay 10.000 – 15.000 DKK per year to be able to forget about book-keeping, VAT (MOMs), paying and reporting salaries, annual accounts and making tax payments. Even on a low annual turnover of 250.000 DKK this might be money well spent if it helps you to avoid 800 DKK fines for late reporting.