Question asked in phd application form - How you intend to fund your studies

For PhD studies in the UK, funding and admission to the program are usually separate steps. Funding opportunities will generally marked explicitly as such, and many of them are only available to UK/EU citizens resident in the country. If you are just applying for admission to a PhD program, there is an expectation that funding is taken care of separately.

The "ideal" answer for such the question regarding the funding source in a UK PhD application takes the form "I have been awarded the following competetive scholarship which will cover all my funding requirements". Other good typical cases are "My employer (company or government agency) really wants me to do a PhD and will foot the bill". These answers strengthen the application, because they show that someone else is sufficiently convinced of the whole PhD thingie to put a significant amount of money behind it.

"Neutral" answers are "I/my parents are rich and we can just afford this" or "I'm getting student loan from XY". Be prepared to provide evidence of claims like this! These answers mean that funding is taken care of, but don't add to the application beyond that.

"I'll get a part-time job" is NOT a good answer. University regulations typically restrict how much work PhD students are allowed to do, and with that number of hours it is probably not even feasible to cover cost of living, not to mention university fees. Anyone who needs a student visa to come to the UK is subject to even stricter regulation, which will actually be enforced. For the universities, the rationale is that PhD students who spend a lot of time working for a living, and a lot of energy worrying about how to make ends meet are far more likely to underperform or even fail than PhD students focused on research.

The main purpose of this question is not to receive your detailed answer on where you will get funds from. It mostly to receive a confirmation from you, in a form of official statement in your application, that you are aware that PhD is going to cost you money and you have a sensible plan where the money will come from. This is mostly to prevent late complaints such as:

No-one told me I will have to pay for this, surely PhD is more like work and it is University who should be paying me.

or

My friend did a PhD with you last year and they payed for the first year OK but then they got these classes to teach which covered years two and three, and I expected the same deal to be available for me.

From University point of view, candidates who are likely to drop out early due to financial problems are best to be avoided. Hence, Universities always prefer candidates who come with external funds (stipendship) covering tuition fees and living expenses and providing some reasonable accommodation for parental leave or long-term illness. In general, such funds are very competitive and hard to get.

Failing that, a candidate can fund their own studies themselves. Often there is no need to explain in details where the money are going to come from. Saying "I'm going to work part time" is not going to make your chances much better than a brief statement "I will fund studies myself" or "My parents will support me". Both are less than ideal, but your PhD application is not likely to be rejected just because of this.