Recently had injectors changed and cam belt at same time on 2002 petrol clio. The car seemed to be using a lot of oil although there was no sign og oil leaking or smoke coming from the exhaust. The car started to make a lot of noise and have now been told the big end has gone. What could have caused the big end to go?

SOURCE: Renault Clio overheating

HI IS THE HEATER INSIDE THE CAR WORKING AS GOOD AS IT NORMALY DOES.
IF THE HEATER IS NOT AS GOOD AS IT WAS OR IS COLD YOU MAY HAVE A START OF A HEAD GASKET GOING AS YOU WILL HAVE AN AIR LOCK IN THE WATER SYSTEM THATS WHY YOUR CAR IS RUNNING HOTTER I HOPE THIS IS HELPFUL TO YOU CHEERS STEVE

SOURCE: 1993 TOYOTA TERCEL 1500cc Valve Seals Replaced now smokes much worse

You either have had the wrong valve seals installed, they are physically missing, or the valves are incorrect (too loose in the guides/stem too thin). The rocker arm seals will not contribute to your issue. If it did not have the oil smoke before you took the head off, the issue is with whatever the machine shop did. Valve seals have to fit TIGHT, or oil will go down the valve stem into the intake.
Take the head back to the machine shop & tell them to fix it. For free.

SOURCE: audi engine oil leak?

Sounds like a leaking valve cover gasket. The parts are around $50 to do both cylinder heads from www.ecstuning.com. It's not a major issue, but it may be a sore point to a potential buyer.

SOURCE: White smoke from Exhaust

hardly likely the exhaust job would cause that, but yes it sounds like you got a blown head gasket. badl lock stricks hmm! also preasure test cylinder head for leaks

SOURCE: i have a 1987 suzuki samurai and have white smoke

Are you losing coolant? If so then you could have a cracked head on the exhaust side and it is leaking coolant into the exhaust and being burnt.