I'm about to submit my HSMP application and I'm a little nervous

Status: In country (worked 11 months of Working Holiday Maker visa)
Total Points Claiming: 85
Qualifications:
- Bachelors Degree- 30 pts (from an Australian university)
Previous Earnings:
- 30 (Claiming for wages earnt in the UK on WHM Visa)
UK Experience
- 5 pts (worked 11 months/ 2 jobs in UK)
Age
- 20 pts
Documents that I will submit
- Cover Letter
Qualifications:
- Original Degree Certificate
- Original Letter from Institution (states my degree was taught in English)
- Original academic transcript
Previous Earnings
- Wage Slips - These are in a security sort of break open slip from a UK company but don't have company logo on them. They do state the company name though
- Bank Statements (I will highlight my salary being paid in)
- Letter from employer stating current wage, gross amount earned, job title and saying that the company I work for is not yet able to produce a P60 form
Age Assessment
- Original Birth Certificate
- Original full driving license
- Notarised copy of passport
English Language
- Degree
- Letter from university saying degree was taught in English
I am a little concerned about my earnings criteria as work can't provide me with a P60 this month despite it being end of financial year in the UK. Will I have any problems with the bank statements and letter from employer as I don't want to make a £400 mistake. I have also changed jobs last year so I'm not sure if I will need to send them my P45 from my last employer?
In regards to the working holiday maker visa, should I wait until I've worked 12 months in the UK before applying or should I apply now? I was a little worried about working past 12 months as this is all I am supposed to work on this visa type. Can I still work over 12 months if my HSMP is being processed?
Thanks all.
Dave