SAR Bloke
It is normal to discuss salaries before tax as you may have other incomes or savings that affect your take home...
You haven't imcluded NI in your tax figure for the £70k FRI, so it will probably come to around £38-40k after 40% tax and Ni. I can't be fagged to work it out. However it will equate to £600+/month in your pocket if you want to look at it that way over the 6 years. Not to be sniffed at I would suggest?
Best
LJ