((((((Rio))))))
nothing is wrong with you.
please don't take this the wrong way but you know the job hunting market in the UK is ruthless atm....and perhaps the only thing "wrong" is your lack of confidence shows?
i know it sounds ridiculous but try standing in front of the mirror for 5 mins each day and telling yourself you ARE worth it, you DO matter and you CAN get there ok?
and btw..volunteering classes as work experience...i started out working in a hostel (night shelter) as a volunteer and next i knew i was a case worker.

then i volunteered as a credit union volunteer and that resulted in a job working finance for the city council.
employers in the UK put a LOT of stock in voluntary work Rio, so DON'T give up ok.
sorry i can't be of more help