Two points:
Eventually is quite right. Pay more claim more. The officers' tax allowance relieved at 20% was EXACTLY equal to the replacement costs of standard working dress over a 5 year life cycle. This was about 10 years ago and the relief had been frozen fir some time. Worth doing a costings exercise again.
Mess dress, No 1, Oxford Shoes, Caps, Brown gloves etc are all extras. Same would be true of a woolly pully changed more often than 5 years.
MMA, the award of MMA for a detached course might be for fewer journeys than you actually did. For instance you might be reimbursed for one return journey over a fortnight but you made two or more - claim the full mileage - petrol receipts can help.
You can also claim for Subsistence where your food costs are more than your allowance. Same with mess charges for accommodation and laundry*. Receipts again.
*That is for those in private or quarters and not those ordinarily in mess. Not sure about bean stealers but there is potential there.