What Matt has suggested will work well also Chris; just a matter of convenience for the technique being used.
To get a good, thin, final clear coat, without building-up the layers too much, especially without the use of an airbrush, try this method.
Use 'Future' as you would for a gloss clear coat, brushing on and letting it find its own level. But, for a matt finish, or a semi-matt finish, add any matt acrylic varnish, and/or Tamiya Flat Base. It will need a little trial and error/ experimentation to achieve the desired sheen etc, but it works brilliantly, and dries without brush marks, unlike 'normal' acrylic or matt varnishes.
NOTE:- Do not add too much Flat Base to start, ot it will dry with a white deposit. Better to add a bit, check the result, and so on. It doesn't take long, as it dries very quickly, and you'll soon be in business.