Installed El Capitan, now I've lost everything. HELP...

Hi all. I will try to keep this short.

I installed El Capitan and migrated all my stuff over from my Time Machine back up. All seemed to work OK except for Safari which crashed every time I clicked in the address bar and I couldn't boot from my Bootcamp partition anymore. I tried to troubleshoot the Safari problem but Console crashed every time I tried to open a crash report. I couldn't find any solution on these forums which helped me either. So I decided to restore my Yosemite set up from Time Machine. Time Machine started doing it's job but stalled half way through wiping my HDD so now I have a crippled Mac.

Cut a long story short, after a lot of messing about I have managed to restore the Mac with a clean install of 10.11 from recovery mode and everything works but this is the big problem. Now I can't restore anything from my back up. Migration asstanst says its copying data, apps etc etc but actually copies nothing over. Time Machine won't let me access any of my backups older than my first attempt at installing El Capitan.

I am at my wits end. Luckily all my photographs are kept on an external HDD but I have lost everything else even though it was backed up. Documents Apps, everything.

Has anyone got any suggestions as to how I can access those backups please. They are all there, I can see them in the finder, but I don't have the permissions to access them.

Any help would be greatly appreciated.

Derek.

27" Retina iMac. 16GB Ram. 1TB Fusion Drive.