I would like to make a one piece mould (less work) of the front of my Elan so I can make a one piece flip front. The bonnet will be fitted and blended in prior to making the mould. I can't see any locks. The mould should flex around the wheel arch lips. Can anyone see any problems?

If prepreg goes wrong, you could likely fix it with a fair amount of 2k filler (If you are still planning to paint it). At least if you get the bagging right, for wich you have several tries for a few pounds.
Infusion can result in parts, wich are half unimpregnated.
It  could be infused, no question. But it is a complicated part. Prepreg scales more user friendly when it comes to bigger and more complex parts.