Any Field Experience must be undertaken with a suitably qualified gas fitter who has the required competency certs and is gas safe registered. It must be auditable and preferably witnessed by a registered field assessor otherwise on completion of your ACS Competency certs and without any solo experience you are not likely to get very far. Infact you will likely be expected to work with a gas company for a couple of years under their umbrella just to gain sufficient solo experience to go solo.
If you are still at your early stages then you must consider what is ahead. Your end goal is clear and achieveing it will be possible if you take the correct steps. The colleges are filled with students money, yet the field is filled with too many new guys who do not have sufficient if any solo experience, a bunch of ACS Certificates, little if any confidence, no mentoring support and A licence that can just as quickly send them to prison, as many are finding out. Unfortunately there are also a great deal of students who have their acs and no-one who wants them, far more still who never get their acs certs because they were unable to complete the most improtant part of the nvq or c&g which is the field training and assessment.
Those people who go on to be successful in this industry are more often those who are already working in it. Almost everyone starts off realising their DIY skills are good and then find a paying outllet for these skills via a local company. The plumbing qualifications should act as a motivator for you to take your existing skills, learned skills and confidence into the market. If you are self employed get your plumbing certs and get out there. Most self employed plumbers dont have any qualifications, they have confidence, and it is that which gets them to where they are. If your goal is to be a gas fitter start work as a plumber. You will soon meet up with other industry engineers who want to share work with you and vice versa.
There are loads of expanding small business gas fitters in shiny vans out there using plumbers to help them now, and paying them for their plumbing skills. These same fitters are even training their associates on the job so they can become gas registered and help share the workload. This is fact. I have met 3 gas fitters in the last 7 days who are bringing plumber mates into the gas to assist them, and in return assisting with the portfolio while the plumbers are doing their gas certs part time or day release.
My advise, get your plumbing, get in the field, get confident, meet people. You will not only be earning money but you will also be achieving your dreams. I am sure there are many people on here who would vouch for that. Doing a whole lot of college or classroom training then hoping someone will take you on 'pay free' so you can go solo is a long stretch. You may be asked to do it yourself sometime. The problem is, unless you are already in the field and your skills are of benefit to the fitter you are likely to half his income and slow their day down to a snails pace. Friends help their friends only when it benefits them too! Imagine what its like when you ask a stranger. You need to be in the field first and then you stand the highest chance of advancing confidently and competently. Doing loads of pipework, hanging radiators and plumbing in boilers is not going to get you a Gas Safe Card ! This card says that you are a representative of the HSE and are capable of identifying unsafe situations and rectifying or making safe in every house you enter, even when you are not at work. That means getting a broad band of experience on different appliances and installation types. Actually applying your theory in the field and confidently making your own decisions.
If you are already self employed, get your plumbing and start plumbing while you aim for your gas. Otherwise get your plumbing cert and find work with a gas, plumbing and heating company. they may even pay for your College training and your portfolio is no longer just a portfolio, it is proper inhouse training which is how most engineers came into this field. Unfortunately many of them have now retired and we do need some competent new blood.
Advise Only ! Follow your heart, but ask yourself the real questions. Put yourself in the gas fitters shoes and think, what would i do ?
If you are a mature student there are other options. Many Accredited Assessment centres are running managed learning programs which include work placements, but remember you still have to get that solo experience somehow and somewhere or sufficient solo assessment to go it alone safely. If its a matter of cost then i am back where i started, get out and use your current skills, then your learned skills to fund your training. The sooner you get out and meet people and can actually show them what you can do and what your value is, the sooner you will realise your dreams, and you will be building a valuable client base at the same time.
Best of Luck out there,
P.s. Just my opinion. I am sure you will get many opinions and from them all dig out the advise that best suits you.