absolutely correct in my last post, phone h&S or gas safe there in no question on this absolutely. If you think otherwise you need to do some revision and get specific answers to your thoughts. The original post was can I service my gas boiler If am not gas safe registered. The answer is no you cant. Nothing to do with competetance..read the regs
A bit of a quote from the regs.
Regulation 3 Qualification and supervision
(1)
No person shall carry out any work in relation to a gas fitting or gas storage vessel unless he is competent to do so.
(2) The employer of any person carrying out such work for that employer, every other employer and self-employed person who has control to any extent of such work and every employer and self-employed person who has required such work to be carried out at any place of work under his control shall ensure that paragraph (1) above is complied with in relation to such work.
(3) Without prejudice to the generality of paragraphs (1) and (2) above and subject to paragraph (4) below, no employer shall allow any of his employees to carry out any work in relation to a gas fitting or service pipework and no self-employed person shall carry out any such work, unless the employer or self-employed person, as the case may be, is a member of a class of persons approved for the time being by the Health and Safety Executive for the purposes of this paragraph.
Guidance note on 3:3
45 Anyone who does work on a gas fitting or gas storage vessel must be competent to do so, whether or not they are required to be a member of an approved class of persons.
Therefore, do-it-yourself installers and those performing favours for friends and relatives all need to have the required competence. The level and range of competence should match the full extent of work done, but needs only to be sufficient for and relevant to that work. Employers of gas fitting operatives are also required under regulation 3(2) to ensure that their employees have the required competence for the work undertaken; in addition to ensuring they are properly experienced and trained (see paragraph 47), this involves ongoing monitoring of performance standards, as necessary.
And from COP20
7 Employers of gas installers will not be complying with their duties under sections 2(1), 2(2)(c) and 3(1) of the Health and Safety at Work etc Act 1974 (HSW Act) or with Regulation 3 of the Gas Safety (Installation and Use) Regulations 1984 if the installer is not competent. Similarly, a self-employed gas installer will not be complying with his duty under section 3(2) of the HSW Act or with Regulation 3 of the 1984 Regulations if he is not competent.
An employee or a person working on his own behalf (viz D.l.Y) will not comply with Regulation 3 of the 1984 Regulations if he is not competent.
Anyone doing DIY work on gas does NOT need to be registered with Gas Safe BUT they DO need to be competent.
The answer to the original question of can i service my own boiler if i am not Gas Safe registered is yes if you are competent.
Competence in gas installation requires enough knowledge, practical skill and experience to carry out the job in hand safely, with due regard to good working practice.
Proving it other than by doing ACS is a bit more difficult.
unless you live in a caravan on your own in the middle of nowhere, in which i would say 'go for it!!!!' the only person you can kill is yourself 
