Nikki Sinclaire, who represented the West Midlands region in Brussels and Strasbourg until 2014, is on trial for allegedly submitting "significant" expenses claims that prosecutors say she knew to be false.
Giving evidence for the first time at her Birmingham Crown Court trial on Monday, she said: "Staff had access to the office credit card and also my other credit card - they knew the numbers."
She added that her "immense workload", representing five million constituents, meant she probably gave "mundane" queries about her travel arrangements from her own staff short shrift and "did not know" what they did with her receipts once handed over.
The 47-year-old said she had "so many objectives to achieve" politically, she expected her expenses to be dealt with by her office.
Sinclaire also told how she had sought "clarification" from the Brussels' parliamentary expenses officials on how to make claims, after being handed a "foot-and-a-half"-high pile of EU paperwork.
Describing her background, she told the jury she was born in 1968, one of four children to a lorry driver father and a nurse mother, and grew up in south London.
She charted how she knew from the age of four of her issues regarding her gender identity and had gender reassignment surgery in 1995.
In emotional testimony, she described how she saw herself as "the first person ever to be in that situation to be elected".
She said: "I wanted to show that somebody like me could do that job."
Recalling her rise within the party, the former MEP added that throughout her time with Ukip from 1997, there was hostility and distrust between her and Nigel Farage.
But she said: "There was also an element of respect - we were two different wings of the same party."
Asked by her barrister Sean Hammond if she had dishonestly submitted 10 claims, she battled tears as she replied: "No.
"I wanted to be different, I wanted to show it was possible to positively represent people."
Sinclaire herself went to the EU anti-fraud unit and the police when she claimed to have realised all was not right with her claims.
She claimed her approach to making expenses claims was to empty out a handbag full of receipts and leave them on desk of her office staff to deal with, as it was "not really my skillset".
Instead, she left the task was down to her UK office administration assistant Paula Murray, or her political aide and later office manager John Ison to sort them.
Sinclaire said: "On a Friday afternoon, I would empty my handbag of all receipts, and put it by John's (Ison's) desk.
"After employing Paula, it would be on her desk."
Sinclaire also claimed that new MEPs were not shown the ropes of the parliamentary expenses system and instead relied on a "fresher's fair" held in Brussels, and a huge bundle of documentation.
Having to set up her office from scratch, she recruited West Midlands regional party worker and Ukip campaigner Mr Ison to help her with setting up the rules and procedures of her administration.
In August, 2009, seeking clarification about the expenses paperwork, she went with Mr Ison to the parliamentary cash office in Brussels to speak with the bureaucrat in charge.
Mr Hammond asked: "So at that stage in terms of physically pulling together of expenses claims and the paperwork, things like that, who took over the administration work?
Sinclaire replied it was Mr Ison who set up the system and he who supervised its function.
Sinclaire said: "The time I spent in my office, the workload I had, I spent so little time in the Birmingham office.
"There were many pressures because of my position.
"I probably wouldn't have reacted well to being asked a mundane question about my claims."
Asked by Mr Hammond how travel bookings were arranged, she said these were dealt with by her staff who had access to her email account, credit cards and passwords.
Sinclaire claimed she was actually attempting to highlight what she alleged was the wastefulness of the EU bureaucracy and expenses system, during her tenure, which ended in 2014 when she failed to get re-elected.
Sinclaire, of Shirley, Solihull, West Midlands, denies misconduct in a public office between October 1 2009 and July 31 2010 while a serving member of the European Parliament by making or causing to be made false or dishonest claims for travel expenses.
She further denies a charge that between October 14 2009 and December 31 2010 she fraudulently transferred criminal property into her bank account.
The trial continues.