I would also give something to St Dunstans - a charity which helps disabled ex service people. Some of them are more or less abandoned once they leave the service and end up with severe mental problems and on the streets. Unlike the boat people who are kept in luxury at tax payers expense.
There is actually lots of help from charities and statutory agencies for ex forces personnel. However, once someone is in the grip of an addiction, or has certain mental health issues, getting them to engage with support agencies isn't always successful. Ask anyone who is at the sharp end of working with rough sleepers.
If I won a million, we'd move to a detached bungalow with a proper workshop/studio for my OH. We'd share a bit with family, it would be nice to give the grandkids enough to pay them through uni or as a house deposit, and donate to a couple of charities, a local homeless support group, and the BHF.