Will, a very quick note:

Tartan shirt with tartan kilt? NO! Please don't do it - it would look dreadful! How much smarter you'd look with say, a navy blue shirt (and plain bottle green tie, if you are wearing a tie), OR a bottle green shirt (and a plain navy blue tie!). With these the best 'look' would be to have your hose match your tie in colour.

An alternative would be a beige or natural shirt with similarly coloured hose.

Always try to avoid patterned shirts, sweaters, etc with a tartan kilt. Plain, self-coloured garments above the waist work best, and allow the kilt to take all the glory!