Bongo Fury

Can anyone help please. Went out yesterday morning ..did about 50 miles. Went to start up last night...no glow plug light and no engine turnover. New battery. Came out this morning started ok..did 15 miles. Just went to start again...same thing. Had new rad 2 months ago which was when the problem started. Has happened about 4 times now. Can't use her as cannot guarantee she will start for trip back. New 100 fuse put in.
Left 24 hours...tried...no light but engine made noise as I let go of key. Tried again...glow plug light now on and started ok several times. Any ideas please

Check the battery connections on the starter battery also the -ve cable termination on the chassis, they may have removed the battery whilst replacing the radiator and you may have a loose connection, which would explain why there are no lights.