Obs cops,
Good effort on the costs.
You need to add fees for approach, airways and landing fees for the IR (unless you are in a Duchess which does not attract airway fees).
Also, accommodation costs if the IR/CPL is done away from home. Also the MCC might need the odd night in a B&B. I spent around 10 weeks in a B&B.
The hour building requires landing fees too. You will, as a minimum need the two landings in the 300nm x-country.
The 100 per hr is a very conservative figure. I would argue 120 min if done in the UK.
I would say 50K. Keep 10% contingency, since you might need extra hrs, exams, tests. You never know.
I never kept a running total, but I was over 50K, since I did hr building abroad, and never went for the cheapest option.