Based on what you have provided, I have put my own estimates. I have not made adjustments for your holidays and personal spending as this is suited to your quality of life.
However, some of your expenses are hugely excessive/ Over-charged.
For example:-
1. If you are paying such high Insurance then you should seriously look into changing your broker. £2100 is too much unless you have points/claims/convictions.
2. Tax? Do you mean road tax? I dont remember paying £600 a year!!
3. Health insurance- the national average for 25-35 year olds is £35 pm. Unless this is a pension plan.
4. Servicing costs- even with running 2 cars this should not be that high. I agree that there will be an initial modification cost if you decide to take that route, but unless you decide to Santa Pod it every weekend these will not be repetative.
5. Mobile phone, TV and internet- You are paying a total of £160 pm. With deals from Virgin and Sky offering TV,Internet and home phone at £50-60 per month ALL IN, and 1200 mins + 600 text for £40-45 pm from nearly all mobile phone companies, you could save yourself £60-70pm.
Based on your personal spending, if it were me i could easily knock off another £800-1100pm. And I have a good social life.