Ask HN: Free software for UK digital taxation?

The UK Gov't have a project to overhaul the taxation system here, called Making Tax Digital (MTD) [0]. At some point this year the plan is to implement the new system for VAT [1], followed by expanding to the rest of the system by 2020.

Gov.UK has a long list of companies [2] providing the software required under the new system, be it a bespoke accounting program or just a specially-formatted Excel spreadsheet or piece of 'bridging software'.

Does anyone know of any free software options available for complying with this new system?

This thread on GnuCash [3] suggests it may not be possible due to the use of per-application secrets, but maybe something can be done with LibreOffice? The use of one non-free spreadsheet would be more palatable than an entire piece of software.

[0] https://en.wikipedia.org/wiki/Making_Tax_Digital [1] https://www.gov.uk/government/collections/making-tax-digital-for-vat [2] https://www.gov.uk/guidance/software-for-sending-income-tax-updates [3] http://gnucash.1415818.n4.nabble.com/UK-specific-MTD-Making-Tax-Digital-tp4691090p4691095.html