This is great! Many thanks for this. Just gave it a go and works a treat. I've amended a tadge as was finding I was getting a full day for last year and only a part day for this year so was slightly skewing the results.
To amend I applied the following:
For Current MTD, set the rolling dates to: START: start of current month END: end of current day minus 1 day
For Last Year MTD, set the rolling dates to: START: start of current month minus 12 months END: end of current day minus 366 days