If the average UK dietary intake were optimised to comply with the WHO recommendations it would save almost 7 million years of life lost prematurely in the UK over the next 30 years and increase average life expectancy by over 8 months (Milner et al., 2015).
Costs
Scarborough et al., 2010 estimated that if the UK followed the Less Meat diet we'd save £0.85 billion in NHS costs, £1.2bn if Fair Less Meat were achieved. If we scale this cost up to 2023:
850000000 * (1.025^13) * 1.079311072
Also see
Barton et al., 2011 argued that a 1% reduction in CVD events across the population would save the NHS £30 million. That was for 50 million people (England and Wales). Scaled to all of GB and assuming healthcare spending is the same in Scotland and Ireland, we multiply that by 67000000/50000000 to get 40.2M for all the UK in 2011, if we inflate that to 2023 that means multiplying by 2.5% over 12 years. We found a 10% meat reduction reduced risk by 1.35% so we scale the saving by 1.35 and this gives us the savings that we could expect from 10% meat reduction.