worcester 350 combi low pressure/leaking?

hi, my combi 350 worcester loses pressure slowly and i have totop it up,the other night it was on low pressure . we topped it up but later when CH came on there was water coming from bottom of boiler...could the pressure to high make it leak???
Its about 12 yrs old or older.

can anyone tell me why it would leak? what should i do?