Anyone have benchmark data on setting an annual L&D budget? I have some mixed data, some say a minimum of 1% of the revenue and some say it averages at £800 per employee. I'll obviously take the 1% option because its a lot more. 

The HR membership organisation for your country will likely have some survey data on this. I recall doing a review a while back and the 'gold standard'/best practice was a week/5 days of training - although, as mentioned elsewhere, context is relevant so this may not make sense for all types of staff.

Following, struggle with external benchmarks. Curious to know what to give min 1% and £800 per employee?

The L&D budget that I am responsible for managing is for our leadership and professional workforce.  (It does not include our hourly workforce nor the regulatory and compliance related training that is required in our industry.)  We have not proposed an L&D budget based upon external benchmarks because they are generic and without comparable business justification.  Our proposed annual budget is largely driven by our standard program costs, ongoing and new initiatives driven by the needs of the business and typical annual inflationary adjustments.