Captain Spam Can, you are on the money concerning France, but...
SFO: 7300€/month before tax, if you are on UK NI, you can't be on French tax so you have to pay according the treaty between the UK and your country of residence. (eg 30% if you are a UK resident up to 50% if you live in some other countries). So take home 3700€-4900€ (2900£-3800£) and almost NO pension at all, company pension 0, UK state pension if you pay for more than 11 years, which may be impossible due to the new EU law.
This new law now puts you on French social security, pay BEFORE tax 5800€, after taxes, depending on your country of residence, 2700-3300€ (2100-2800£) but good French pension, if the system still exists when you retire.
If you are a French resident take home +/-5000€/month after taxes and good pension.