Calculating Tax For Pro Sites and Membership 2 Pro

Hi there. How do I set up tax calculations for UK VAT within Pro Sites and Membership Pro 2 without paying for the additional cost per transaction of Taxamo?
All membership and ecommerce software I have used previously simply calculates the tax within the plugin or software, not referring to an external paid service.
From what I see there is no alternative? this seems nuts to me to have no internal option.