Main bonding is required to incoming metallic services (these are usually the water pipe and the gas pipe, but, if present, oil lines, aircon pipes, ventilation ducts, iron or lead drainpipes etc) where they enter your home. They should be connected the main earthing terminal which will be close to, or inside, your consumer unit.
A useful pic is on https://www.diynot.com/wiki/Electrics:main_equipotential_bonding
The green and yellow cable size required can be calculated, but in an ordinary house, the calculation is pretty sure to say 10mm, so use that unless you know different.
You do not have to bond metal sinks, windowframes, taps, radiators etc
Post a pic of what you have if you need particular advice.
A useful pic is on https://www.diynot.com/wiki/Electrics:main_equipotential_bonding
The green and yellow cable size required can be calculated, but in an ordinary house, the calculation is pretty sure to say 10mm, so use that unless you know different.
You do not have to bond metal sinks, windowframes, taps, radiators etc
Post a pic of what you have if you need particular advice.