THERE IS A LOUD KNOCKING NOISE WHEN I START ENGINE!!!!I VE BEEN TOLD ITS THE BIG ENDS GONE !!!!!IS THIS TRUE!!!!AS I AM UN SHORE AS THIS IS MY FIRST SCOOBY!!!!

 

its bigends mate the shells & crank are made of chocolate and just melts resulting in play on conrods knocking against crank . you now have 3 options
1 rebuild costly option but 100% sure £1500 >
2 2nd hand engine but 50% sure £500>
3 sell car as spares repair and cut losses £0

if it was me i would just drop 2nd hand lump in and sell car and look for another with low miles / recent engine rebuild with receipts / service history / un modified .