I have a mk1 Octavia TDi 110 and it keeps blowing a 50amp fuse on the battery fuse box and it's not charging the battery there are no warning lights on but alt is throwing out 14.5 volts at the back of the alt,I've had it in the garage and rest the key part of it and told me that there is something wrong with the glow plug side and that's why it not charging any ideas of where to start looking for the fault and what to test and check

Check the fuse block on top of the battery, particularily look for signs of corrosion & melting on the thick black & red cables where they connect.  There's a known issue with poor crimp connections on the Alternator & starter motor cables on mk1 Octy's causing all sorts of electrical problems.

I took a big brown relay out and its a double relay what dose this relay control I know it controls the wipers but it controls something else as well

4 glow plugs from memory have to be approx. 60-80 ? amps   sounds like a glow control/relay problem but I don't have any experience with these

I'd start by checking the battery top fuses again, just to be certain that they and their carrier are not melted.

 

After that, if the garage are correct, then either the glowplug controller is FUBAR or the relay is stuck "made".