I’ve never tried it with midges, but insects reeeally hate anything with tea-tree oil.
You can get tea-tree shower gel, etc.
I found the essential oil in the bargain dept, in a big Tesco’s. 10ml for £1.
I’d dilute it one part tea-tree essential oil to ten parts vegetable oil.
This might be an opportunity to use your hip flask and funnel gift set.
It turns out that tea-tree oil is also very bad news for pets and you’re not supposed to use the essential oil directly on your skin (topically), and never ever ingest it😭
But, you can drop a diluted solution onto your bike helmet and clothes.
Id also carry another hip flask, (correctly labelled), with an alcohol based mouthwash. Not only can you sanitise your hands, but you can apply it to any insect bites to reduce the swelling.
Or a hand-gel may work too.
Good luck!