1.8 Ford Escort Diesel Drive Belt - Can I fix it?

I have a 1.8 Ford Escort Diesel Car, K reg. The Drive belt has snapped. It's obvious that the valves have bent but will the whole engine and pistons have broken too? I've heard that it can be an expensive job if I have to replace the whole engine. I am hoping I will just need a new head, belt and a speacialist to do the timing/

Thanks,

Shaun