rear lights etc

ok new on here but not to VWs, well new to mk1 golfs lol.
Right my rear lights are playing upwhen headlights teh brake lights light up fine, but when headlights are on, the brake lights and rear lights are the same bulb. Indcators will sometimes come on but mostly wont. All front lights are fine so are number plate lights, also have a spare connecter on back its a 2 block one on a T-shape on the drivers side bit of the loom

only had car a few weeks they worked fine when i brought it home now they have stopped, havnt really done much with it but just insured it today and took my other car off the road.

Any ideas cheers