Do you know if the U.K Singer 6180 Is able to use a double needle

It may be the same as the Brother E6

https://www.google.com/search?q=6180+singer+brilliance+E6+error

I fixed your question.
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increase the needle thread tension up more

It appears on page 27 of the manual that there is a way to manually set the needle to 13 different positions using the stitch width control. You might need to set it to straight stitch function first.

Clean the bobbin case area thoroughly, including removing the actual bobbin case. Vacuum and lint brush, no compressed air. Reassemble. If that doesn't do it, it's time to take it in to the shop.

call or email these sites and ask them about the part
sewvacdoctor.com
a1sewingmachines.com

E7 means the machine has 'had enough' and that error flashes to let you know it needs a break. I found that out by trial and error and after phoning Singer as well.

Try www.fixsewingmachine.com for FREE videos, pictures, machine timing, tension fix, etc. Better then owner's manual! Jimmy

Go to www.singerco.com and under customer support, you will see instruction manuals, now enter 6180 in the box, and voila, a free copy of your manual to download.

Change needle
Clean under needle plate where feed dogs are for lint
Clean bobbin area for lint or loose threads
Rethread machine top thread make sure to get every thread guide
& bobbin
Check tension 3 or 4 is usually good

You may have the needle in wrong. Check to be sure it's positioned correctly, The groove down the center of the needle should face the front of the machine. And be certain the needle is pushed completely up in its holder. If neither of these work, you might just double check the bobbin!